Method for manufacturing pneumatic tire

ABSTRACT

In a method for manufacturing a pneumatic tire, molding of a green tire has an assembly step of bonding an inner liner and an unvulcanized rubber sheet with end portions thereof in a width direction being displaced from each other by 50 mm to 500 mm in the width direction to manufacture a laminate, cutting the laminate to have a constant length corresponding to a width of a drum to manufacture a cut sheet, and a joining step of winding the cut sheet on entire circumference of the drum such that a cut surface thereof extends in a circumferential direction of the drum and the inner liner is disposed on an inner surface side, and joining the end portions of the inner liner and joining the end portions of the unvulcanized rubber sheet such that positions of the joined end portions are displaced by a constant distance.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a pneumatictire, in particular to a method for molding an inner liner, and to amethod for manufacturing a pneumatic tire including the step of moldinga green tire by manufacturing a laminate of an inner liner and anunvulcanized rubber sheet such as a carcass ply.

BACKGROUND ART

Recently, weight saving of tires has been pursued because of strongsocial demands for fuel efficiency of automobiles. Of tire members,weight saving has also been required for an air shutoff layer (innerliner) which is disposed inside a tire and is required to reduce leakageof air from the inside to the outside of a pneumatic tire.

At present, for a rubber composition for the air shutoff layer, a rubberformulation mainly composed of butyl rubber which contains, for example,70 to 100% by mass of butyl rubber and 30 to 0% by mass of naturalrubber is used to improve air permeation resistance of the tire.Further, the rubber formulation mainly composed of butyl rubbercontains, in addition to butylene, about 1% by mass of isoprene, whichallows intermolecular co-crosslinking with an adjacent rubber layeralong with sulfur, a vulcanization accelerator, and zinc white. Thebutyl-based rubber having a general formulation is required to have athickness of about 0.6 to 1.0 mm for tires for passenger cars, and athickness of about 1.0 to 2.0 mm for tires for trucks and buses. Topursue weight saving of tires, there has been a demand for a polymerwhich is more excellent in air permeation resistance and allows afurther reduction in the thickness of the air shutoff layer, whencompared with the butyl-based rubber.

In molding a green tire for a pneumatic tire, when an inner liner P ismolded on a drum 5A as shown in FIG. 7, generally, an inner liner filmP2 is bonded to an unvulcanized inner liner rubber P1 beforehand on aconveyer, with positions of both end edges in a longitudinal directionbeing aligned, to produce a laminate, the laminate is wound on a bandover its entire circumference with inner liner film P2 of the laminatebeing disposed on an inner surface side, both end portions of thelaminate are overlapped with each other at one location on thecircumference to form a joint PJ, and thereafter a stitching roller isused to press joint PJ of the laminate and remove air.

In such a technique, since inner liner film P2 and unvulcanized innerliner rubber P1 are bonded beforehand with the positions of their bothend edges in the longitudinal direction being aligned, and thereafterwound on the drum, joint PJ formed on the circumference of drum 5Ainevitably has a large thickness when the both end portions of thelaminate are overlapped and joined on the drum. Thus, even if thestitching roller is applied over joint PJ, air may remain at joint PJ,and if the remaining air expands by vulcanization molding of the greentire, joint PJ of laminate P may peel off.

In addition, since the end portions of laminate P form the joint at onelocation on the circumference of drum 5A in this technique, peeling-offof the joint of the inner liner of the molded green tire may cause adamage to an adjacent carcass ply.

It has been proposed in conventional techniques to use a thermoplasticelastomer for an inner liner with the intention to achieve weight savingof a pneumatic tire. However, the material, which is thinner and has ahigher air permeation resistance than an inner liner made of butyl-basedrubber, is inferior to the inner liner made of butyl-based rubber invulcanization adhesive strength with insulation rubber and carcass plyrubber adjacent to the inner liner.

In particular, if the joint of the inner liner has a weak adhesivestrength, the joint may peel off during driving, which may cause areduction in the internal pressure of the tire, and burst of the tire.Further, since the joint has a structure in which another member isexposed inside, an air leakage path may be formed, and a reduction inthe internal pressure of the tire is likely to be caused.

Japanese Patent Laying-Open No. 2009-208444 (PTD 1) discloses atechnique of molding an unvulcanized tire by bonding an inner liner filmand an unvulcanized rubber sheet with both ends in an extendingdirection being displaced from each other, and winding the tacky body ona drum.

However, in order to displace the both ends in the extending directionfrom each other, it is necessary to cut each member one by one to have aconstant size, and individually bond the members with being displacedfrom each other, which may deteriorate productivity. Further, dependingon the bonding method, accuracy is deteriorated and air remains betweenthe films, which may cause a damage during vulcanization of the tire.

Japanese Patent Laying-Open No. 2007-291256 (PTD 2) discloses apneumatic tire including a rubber composition for an inner linercontaining an ethylene-vinyl alcohol copolymer in the range of 15 to 30parts by mass relative to 100 parts by mass of a rubber component madeof natural rubber and/or synthetic rubber. However, this technique isnot preferable from the viewpoint of weight saving of tires since theinner liner has a large thickness of 1 mm.

Japanese Patent Laying-Open No. 9-165469 (PTD 3) discloses a nylon filmused as an inner liner. The document discloses manufacturing a pneumatictire by subjecting the nylon film to RFL treatment and thereafterbonding the nylon film to a tire inner surface or a carcass layer with arubber cement made of a rubber composition.

This technique has a problem that it results in complicated steps.Further, in a vulcanization step in which vulcanization molding isgenerally performed with an unvulcanized tire accommodated within a moldbeing pressed against an inner surface of the mold from an inner side ofthe unvulcanized tire, the inner liner made of the nylon film sticks andadheres to a bladder and is damaged when the bladder is heated duringvulcanization.

Japanese Patent Laying-Open No. 2010-013646 (PTD 4) proposes improvingadhesive strength by using petroleum resin or terpene resin as atackifier, for an SIBS as a thermoplastic elastomer. However, apolyamide-based polymer is blended in addition to the SIBS, causing areduction in flex crack resistance.

Further, Japanese Patent Laying-Open No. 2010-100675 (PTD 5) proposesimproving adhesiveness with carcass ply rubber by using natural rosin,terpene, chromane indene resin, petroleum resin, alkylphenol resin, orthe like as a tackifier, for a blended material of an SIBS and asulfur-crosslinkable polymer.

However, in the technique of blending 10 to 300 parts by weight of thesulfur-vulcanizable polymer relative to 100 parts by weight of the SIBS,when the sulfur-crosslinkable polymer is less than or equal to 100 partsby weight, the SIBS serves as a matrix (sea portion) and thesulfur-crosslinkable polymer serves as a domain structure (islandportion), and adhesive strength with the carcass rubber at a contactinterface is not improved. Further, when the sulfur-crosslinkablepolymer is more than or equal to 100 parts by weight, gas barrierproperty is deteriorated in other than butyl rubber, and adhesivestrength is deteriorated in butyl rubber. In addition, depending on apolymer to be blended, tackiness is increased, and it is not possible tofabricate a film with a thickness of 600 μm or less.

In International Publication No. 2008-029781 (PTD 6), a tire ismanufactured using strips of a film laminate obtained by blending athermoplastic resin with a thermoplastic elastomer. By employing alaminate, gas barrier property and adhesiveness can be improved, whichenables junction between the ribbon-shaped strips. However, in thistechnique, an unvulcanized green cover of the film laminate has aconstant gauge, and if the gauge is thinned, a vulcanized tire may havea thinned finish at a buttress part or the like.

CITATION LIST Patent Document

PTD 1: Japanese Patent Laying-Open No. 2009-208444

PTD 2: Japanese Patent Laying-Open No. 2007-291256

PTD 3: Japanese Patent Laying-Open No. 9-165469

PTD 4: Japanese Patent Laying-Open No. 2010-013646

PTD 5: Japanese Patent Laying-Open No. 2010-100675

PTD 6: International Publication No. 2008-029781

SUMMARY OF INVENTION Technical Problem

A first object of the present invention is to implement, in a method formolding a tire by winding a laminate of an inner liner and anunvulcanized rubber sheet such as a carcass ply on a molding drum,enhanced uniformity in thickness at a joint on the circumference of thedrum to manufacture a pneumatic tire, prevention of remaining of air,and effective reduction of peeling-off of the joints of the inner linerand the carcass ply. Thus, when the inner liner and the unvulcanizedrubber sheet are laminated beforehand and wound on the drum, the innerliner and the unvulcanized rubber sheet are bonded with being displacedfrom each other in a width direction to manufacture the laminate.

A second object of the present invention is to provide, in a method formolding a tire by winding a laminate of an inner liner and anunvulcanized rubber sheet such as a carcass ply on a molding drum, amethod for manufacturing a pneumatic tire which enhances uniformity inthickness at a joint on the circumference of the drum, prevents air fromremaining, and effectively reduces peeling-off of the joints of theinner liner and the carcass ply. By adopting such a manufacturingmethod, a pneumatic tire excellent in flex crack growth, rollingresistance properties, and static air pressure drop rate is obtained.

A third object of the present invention is to provide, in a method formolding a tire by winding a laminate of an inner liner and anunvulcanized rubber sheet such as a carcass ply on a molding drum, amethod for manufacturing a pneumatic tire which enhances uniformity inthickness at a joint on the circumference of the drum, prevents air fromremaining, and effectively reduces peeling-off of the joints of theinner liner and the carcass ply. By adopting such a manufacturingmethod, a pneumatic tire excellent in rolling resistance properties,static air pressure drop rate, and uniformity is obtained.

A fourth object of the present invention is to provide, in a method formolding a tire by winding a laminate of an inner liner formed of acomposite body having two layers and an unvulcanized rubber sheet suchas a carcass ply on a molding drum, a method for manufacturing apneumatic tire which enhances uniformity in thickness at a joint on thecircumference of the drum, prevents air from remaining, and effectivelyreduces peeling-off of the joints of the inner liner and the carcassply. With such a manufacturing method, the present invention is directedto obtaining a pneumatic tire having improved adhesiveness between theinner liner and the carcass ply, and excellent flex crack growth,rolling resistance properties, static air pressure drop rate, anduniformity.

A fifth object of the present invention is to implement, when molding atire by winding a laminate of an inner liner and an unvulcanized rubbersheet such as a carcass ply on a molding drum, enhanced uniformity inthickness at joints of the inner liner and the carcass ply on thecircumference of the drum, prevention of remaining of air, and effectivereduction of peeling-off of the joints of the inner liner and thecarcass ply. In addition, the present invention is directed to providinga method for manufacturing a pneumatic tire excellent in rollingresistance properties, static air pressure drop rate, and uniformity.

A sixth object of the present invention is to provide, in a method formolding a tire by winding a laminate of an inner liner and anunvulcanized rubber sheet such as a carcass ply on a molding drum, amethod for manufacturing a pneumatic tire which enhances uniformity inthickness at a joint on the circumference of the drum, prevents air fromremaining, and effectively reduces peeling-off of the joints of theinner liner and the carcass ply.

By adopting such a manufacturing method, the present invention isdirected to obtaining a pneumatic tire having an inner liner with areduced flex crack growth, and having excellent rolling resistanceproperties, static air pressure drop rate, and uniformity.

Solution to Problem

In connection with the first object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance,

the inner liner being a laminate of a first layer and a second layer,the first layer being a thermoplastic elastomer composition containing0.1 to 50% by mass of an organic derivative of a clay mineral relativeto 100 parts by mass of a thermoplastic elastomer mixture containing 60to 99% by mass of a styrene-isobutylene-styrene block copolymer and 1 to40 parts by mass of a polyamide-based polymer which contains polyamidein a molecular chain and has a Shore D hardness of 70 or less, andhaving a thickness of 0.05 mm to 0.6 mm, the second layer being disposedon a side of the unvulcanized rubber sheet, made of a thermoplasticelastomer composition, and having a thickness of 0.01 mm to 0.3 mm.

In the assembly step, the inner liner and the unvulcanized rubber sheethave different widths, and both end portions thereof in the widthdirection are displaced in the width direction so as not to overlap eachother, and thereby the laminate can be manufactured.

Preferably, the second layer is a thermoplastic elastomer compositioncontaining at least one of a styrene-isoprene-styrene block copolymerand a styrene-isobutylene block copolymer. Further, preferably, 15 to40% by mass of an ethylene-vinyl alcohol copolymer is contained in apolymer component of the thermoplastic elastomer mixture of the firstlayer.

In the present invention, preferably, the styrene-isobutylene-styreneblock copolymer contains 10 to 30% by mass of a styrene component.Further, preferably, the polyamide-based polymer is a block copolymercomposed of a polyamide component and a polyether component. It is notedthat the unvulcanized rubber sheet is, for example, a carcass ply.

In connection with the second object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance, the inner liner being formed of a laminate of a first layerand a second layer, the first layer containing more than or equal to 60%by mass and less than or equal to 99.5% by mass of astyrene-isobutylene-styrene triblock copolymer and more than or equal to0.5% by mass and less than or equal to 40% by mass of a polymer obtainedby polymerizing a monomer having 4 carbon atoms, and having a thicknessof more than or equal to 0.05 mm and less than or equal to 0.6 mm, thesecond layer being disposed on a side of the unvulcanized rubber sheet,made of a thermoplastic elastomer, and having a thickness of 0.01 mm to0.3 mm.

In the method for manufacturing the pneumatic tire in accordance withthe present invention, in the assembly step, the inner liner and theunvulcanized rubber sheet have different widths, and the inner liner andthe unvulcanized rubber sheet can be bonded such that both end portionsthereof in the width direction are displaced in the width direction soas not to overlap each other.

Further, preferably, the second layer has at least one of astyrene-isoprene-styrene triblock copolymer and a styrene-isobutylenediblock copolymer, has a thickness of more than or equal to 0.01 mm andless than or equal to 0.3 mm, and contains a polymer obtained bypolymerizing a monomer having 4 carbon atoms by more than or equal to0.5% by mass and less than or equal to 40% by mass of a polymercomponent.

As the polymer obtained by polymerizing a monomer having 4 carbon atoms,at least one of polybutene and polyisobutylene can be suitably used. Inaddition, preferably, the polymer obtained by polymerizing a monomerhaving 4 carbon atoms satisfies at least one of a number-averagemolecular weight of more than or equal to 300 and less than or equal to3,000, a weight-average molecular weight of more than or equal to 700and less than or equal to 100,000, and a viscosity-average molecularweight of more than or equal to 20,000 and less than or equal to 70,000.

Further, in the present invention, the styrene-isobutylene-styrenetriblock copolymer preferably has a weight-average molecular weight ofmore than or equal to 50,000 and less than or equal to 400,000, and astyrene unit content of more than or equal to 10% by mass and less thanor equal to 30% by mass, and the styrene-isoprene-styrene triblockcopolymer preferably has a weight-average molecular weight of more thanor equal to 100,000 and less than or equal to 290,000, and a styreneunit content of more than or equal to 10% by mass and less than or equalto 30% by mass. In addition, preferably, the styrene-isobutylene diblockcopolymer is a linear copolymer, and has a weight-average molecularweight of more than or equal to 40,000 and less than or equal to120,000, and a styrene unit content of more than or equal to 10% by massand less than or equal to 35% by mass.

In connection with the third object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance,

the inner liner including a polymer sheet containing more than or equalto 0.1 parts by mass and less than or equal to 5 parts by mass of sulfurrelative to 100 parts by mass of a polymer component containing morethan or equal to 5% by mass and less than or equal to 40% by mass of astyrene-isobutylene-styrene triblock copolymer and more than or equal to60% by mass and less than or equal to 95% by mass of at least one rubbercomponent selected from the group consisting of natural rubber, isoprenerubber, and butyl rubber.

In the assembly step, the inner liner and the unvulcanized rubber sheethave different widths, and a method for bonding the inner liner and theunvulcanized rubber sheet such that both end portions thereof in thewidth direction are displaced in the width direction so as not tooverlap each other can be adopted. In addition, preferably, the polymersheet further contains more than or equal to 1 part by mass and lessthan or equal to 5 parts by mass of stearic acid, more than or equal to0.1 parts by mass and less than or equal to 8 parts by mass of zincoxide, more than or equal to 0.1 parts by mass and less than or equal to5 parts by mass of an age inhibitor, and more than or equal to 0.1 partsby mass and less than or equal to 5 parts by mass of a vulcanizationaccelerator, relative to 100 parts by mass of the polymer component.Further, preferably, the styrene-isobutylene-styrene triblock copolymerhas a weight-average molecular weight of more than or equal to 50,000and less than or equal to 400,000, and a styrene unit content of morethan or equal to 10% by mass and less than or equal to 30% by mass.

In the present invention, the inner liner can be a laminate of a firstlayer and a second layer, the first layer being a polymer sheet made ofa polymer composition containing more than or equal to 0.1 parts by massand less than or equal to 5 parts by mass of sulfur relative to 100parts by mass of a polymer component containing more than or equal to 5%by mass and less than or equal to 40% by mass of astyrene-isobutylene-styrene triblock copolymer and more than or equal to60% by mass and less than or equal to 95% by mass of at least one rubbercomponent selected from the group consisting of natural rubber, isoprenerubber, and butyl rubber, the second layer being made of a thermoplasticresin composition containing more than or equal to 0.1 parts by mass andless than or equal to 5 parts by mass of sulfur relative to 100 parts bymass of a thermoplastic elastomer.

Preferably, the polymer composition of the first layer further containsmore than or equal to 1 part by mass and less than or equal to 5 partsby mass of stearic acid, more than or equal to 0.1 parts by mass andless than or equal to 8 parts by mass of zinc oxide, more than or equalto 0.1 parts by mass and less than or equal to 5 parts by mass of an ageinhibitor, and more than or equal to 0.1 parts by mass and less than orequal to 5 parts by mass of a vulcanization accelerator, relative to 100parts by mass of the polymer component.

Preferably, the thermoplastic elastomer is at least one selected fromthe group consisting of a styrene-isoprene-styrene triblock copolymer, astyrene-isobutylene diblock copolymer, a styrene-butadiene-styrenetriblock copolymer, a styrene-isoprene.butadiene-styrene triblockcopolymer, a styrene-ethylene.butene-styrene triblock copolymer, astyrene-ethylene.propylene-styrene triblock copolymer, astyrene-ethylene.ethylene.propylene-styrene triblock copolymer, astyrene-butadiene.butylene-styrene triblock copolymer, andepoxy-modified thermoplastic elastomers thereof.

The second layer can include at least one of an SIS layer in which thethermoplastic elastomer contains a styrene-isoprene-styrene triblockcopolymer, an SIB layer in which the thermoplastic elastomer contains astyrene-isobutylene diblock copolymer, and an epoxidized SBS layer inwhich the thermoplastic elastomer contains an epoxidizedstyrene-butadiene-styrene triblock copolymer.

In addition, preferably, the styrene-isobutylene-styrene triblockcopolymer has a weight-average molecular weight of more than or equal to50,000 and less than or equal to 400,000, and a styrene unit content ofmore than or equal to 10% by mass and less than or equal to 30% by mass.Further, preferably, the styrene-isoprene-styrene triblock copolymer hasa weight-average molecular weight of more than or equal to 100,000 andless than or equal to 290,000, and a styrene unit content of more thanor equal to 10% by mass and less than or equal to 30% by mass.

Further, preferably, the styrene-isobutylene diblock copolymer is alinear copolymer, and has a weight-average molecular weight of more thanor equal to 40,000 and less than or equal to 120,000, and a styrene unitcontent of more than or equal to 10% by mass and less than or equal to35% by mass.

In connection with the fourth object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance,

the inner liner being composed of a first layer disposed on the innerside of the tire and a second layer disposed in contact with a rubberlayer of a carcass ply, the first layer being a thermoplastic elastomercomposition mainly composed of a styrene-isobutylene-styrene blockcopolymer, the second layer being a styrene-based thermoplasticelastomer composition,

(1) at least one of the thermoplastic elastomer compositions of thefirst and second layers containing 0.1 to 100 parts by mass of atackifier relative to 100 parts by mass of a thermoplastic elastomercomponent, or

(2) the second layer containing a styrene-isobutylene-styrene blockcopolymer by 10 to 80% by mass of a thermoplastic elastomer component.

Preferably, in the assembly step, the inner liner and the unvulcanizedrubber sheet have different widths, and the inner liner and theunvulcanized rubber sheet are bonded such that both end portions thereofin the width direction are displaced in the width direction so as not tooverlap each other. In addition, preferably, the tackifier has aweight-average molecular weight Mw of 1×10² to 1×10⁶, and a softeningpoint within a range of 50° C. to 150° C.

In an embodiment of the present invention, the second layer is athermoplastic elastomer composition containing at least one of astyrene-isoprene-styrene block copolymer and a styrene-isobutylenediblock copolymer, and the first layer is formed to have a thickness of0.05 mm to 0.6 mm and the second layer is formed to have a thickness of0.01 mm to 0.3 mm.

Preferably, the styrene-isobutylene-styrene triblock copolymer has aweight-average molecular weight of more than or equal to 50,000 and lessthan or equal to 400,000, and a styrene unit content of more than orequal to 10% by mass and less than or equal to 30% by mass, and thestyrene-isoprene-styrene triblock copolymer has a weight-averagemolecular weight of more than or equal to 100,000 and less than or equalto 290,000, and a styrene unit content of more than or equal to 10% bymass and less than or equal to 30% by mass. Further, preferably, thestyrene-isobutylene diblock copolymer is a linear copolymer, and has aweight-average molecular weight of more than or equal to 40,000 and lessthan or equal to 120,000, and a styrene unit content of more than orequal to 10% by mass and less than or equal to 35% by mass.

In connection with the fifth object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance,

the inner liner being composed of a composite layer of a first layerdisposed on the inner side of the tire and a second layer disposed incontact with the unvulcanized rubber sheet,

at least one of the first layer and the second layer being made of anelastomer composition containing an isobutylene-based modified copolymerwhich is made of a polymer block (A) mainly composed of isobutylene anda polymer block (B) mainly composed of an aromatic vinyl-based compound,and in which at least one of the blocks contains β-pinene.

In the assembly step, the inner liner and the unvulcanized rubber sheethave different widths, and the inner liner and the unvulcanized rubbersheet can be bonded such that both end portions thereof in the widthdirection are displaced in the width direction so as not to overlap eachother.

Further, preferably, the elastomer composition of the first layercontains the isobutylene-based modified copolymer by 10 to 100% by massof an entire elastomer component, and the elastomer composition of thesecond layer contains the isobutylene-based modified copolymer by 5 to80% by mass of an entire elastomer component.

In addition, preferably, a content of β-pinene in the isobutylene-basedmodified copolymer is 0.5 to 25% by mass.

Further, preferably, the isobutylene-based modified copolymer has aweight-average molecular weight of 30,000 to 400,000, and a value ofmolecular weight distribution (Mw/Mn) of less than or equal to 1.3, andβ-pinene is contained in a styrene block of astyrene-isobutylene-styrene block copolymer, a styrene-isoprene-styreneblock copolymer, or a styrene-isobutylene block copolymer.

In connection with the sixth object, the present invention relates to amethod for manufacturing a pneumatic tire having an inner liner on aninner side of the tire, molding of a green tire having:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other by 50 mm to 500 mm in the width direction tomanufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance,

the inner liner being composed of a composite layer of a first layerdisposed on the inner side of the tire and a second layer disposed incontact with the unvulcanized rubber sheet,

the first layer being made of an elastomer composition containing anSIBS modified copolymer having a styrene block moiety of astyrene-isobutylene-styrene block copolymer modified with an acidchloride having an unsaturated bond or an acid anhydride and having athickness of 0.05 mm to 0.6 mm,

the second layer being made of an elastomer composition containing atleast one of a styrene-isoprene-styrene block copolymer and astyrene-isobutylene block copolymer, and having a thickness of 0.01 mmto 0.3 mm.

In the assembly step, the inner liner and the unvulcanized rubber sheethave different widths, and the inner liner and the unvulcanized rubbersheet can be bonded such that both end portions thereof in the widthdirection are displaced in the width direction so as not to overlap eachother.

In addition, desirably, a blending quantity of the SIBS modifiedcopolymer in the first layer is adjusted in the range of 10% by mass to100% by mass of an elastomer component. Further, desirably, the secondlayer contains an SIBS modified copolymer, and a blending quantitythereof is adjusted in the range of 5% by mass to 80% by mass of athermoplastic elastomer component.

The first layer can be a mixture of the styrene-isobutylene-styreneblock copolymer and the SIBS modified copolymer. Further, desirably, oneof the first and second layers is blended with a tackifier. In addition,desirably, one of the first and second layers is blended with a rubbercomponent by 5 to 75% by mass of an elastomer component.

Further, the method for manufacturing the pneumatic tire in accordancewith the present invention is characterized in that the first layer ofthe inner liner is blended with at least one of an ultraviolet absorberand an antioxidant by 0.5 parts by mass to 40 parts by mass relative to100 parts by mass of an elastomer component.

Advantageous Effects of Invention

As for a first effect of the present invention, since the inner linermade of a composite layer of the first layer as a thermoplasticelastomer composition obtained by blending an organic derivative of aclay mineral with a mixture of an SIBS and a polyamide-based polymer andthe second layer as a thermoplastic elastomer composition is used in thepresent invention, an air-in phenomenon and flex crack growth can bereduced and static air pressure drop can also be improved. In addition,the composite layer and the unvulcanized rubber sheet are laminated suchthat the second layer thereof is in contact with the unvulcanized rubbersheet and the composite layer and the unvulcanized rubber sheet aredisplaced from each other in the width direction, then the laminate iswound on the drum over its entire circumference with the inner linerbeing disposed on the inner surface side, and the end portions of theinner liner and the end portions of the unvulcanized rubber sheet areeach joined at the positions apart from each other in thecircumferential direction of the drum. Thereby, a step difference inthickness at a joint of the inner liner and a joint of the unvulcanizedrubber sheet can be alleviated. In addition, air at these joints can bereliably removed by stitching, and thus peeling-off of the joints due toremaining air can be prevented.

In addition, since the joints apart from each other in thecircumferential direction are formed in the molded inner liner andunvulcanized rubber sheet such as a carcass ply, even if the joint ofthe carcass ply peels off, the peel-off portion is reinforced by theinner liner, and thus damage and breakage of a product tire isalleviated.

Further, since the inner liner is the composite layer of the first layerdisposed on the inner side of the tire, mainly composed of astyrene-isobutylene-styrene block copolymer, and having a thickness of0.05 mm to 0.6 mm, and the second layer disposed on the side of theunvulcanized rubber sheet, made of a thermoplastic elastomercomposition, and having a thickness of 0.01 mm to 0.3 mm, adhesivestrength with rubber of the carcass ply adjacent to the second layer isenhanced. In addition, the inner liner has a high reinforcing effectwhen the joint of the carcass ply peels off, and the carcass ply has ahigh reinforcing effect when the joint of the inner liner peels off.

As for a second effect of the present invention, the inner liner isformed of a laminate of the first layer including a mixture of an SIBSand a polymer obtained by polymerizing a monomer having 4 carbon atoms(C4 polymer) and the second layer as a thermoplastic elastomer in thepresent invention. The inner liner and the unvulcanized rubber sheet arelaminated with being displaced from each other in the width direction,then the laminate is wound on the drum over its entire circumferencewith the inner liner being disposed on the inner surface side, and theend portions of the inner liner and the end portions of the unvulcanizedrubber sheet are each joined at the positions apart from each other inthe circumferential direction of the drum. Thereby, a step difference inthickness at a joint of the inner liner and a joint of the unvulcanizedrubber sheet can be alleviated. In addition, air at these joints can bereliably removed by stitching, and thus peeling-off of the joints due toremaining air can be reduced.

Further, since the joints apart from each other in the circumferentialdirection are formed in the molded inner liner and unvulcanized rubbersheet such as a carcass ply, even if the joint of the carcass ply peelsoff, the peel-off portion is reinforced by the inner liner, and thusdamage and breakage of a product tire is alleviated.

In particular, in the present invention, since the inner liner is acomposite layer of the first layer disposed on the inner side of thetire and having a thickness of 0.05 mm to 0.6 mm and the second layerdisposed on the side of the unvulcanized rubber sheet and having athickness of 0.01 mm to 0.3 mm, adhesive strength with rubber of theadjacent carcass ply is enhanced. In addition, the inner liner has ahigh reinforcing effect when the joint of the carcass ply peels off, andthe carcass ply has a high reinforcing effect when the joint of theinner liner peels off.

As for a third effect of the present invention, the inner liner isformed by mixing an SIBS with a rubber component and dynamicallyvulcanizing the mixture in the present invention. The inner liner andthe unvulcanized rubber sheet are laminated with being displaced fromeach other in the width direction, then the laminate is wound on thedrum over its entire circumference with the inner liner being disposedon the inner surface side, and the end portions of the inner liner andthe end portions of the unvulcanized rubber sheet are each joined at thepositions apart from each other in the circumferential direction of thedrum. Thereby, a step difference in thickness at a joint of the innerliner and a joint of the unvulcanized rubber sheet can be alleviated. Inaddition, air at these joints can be reliably removed by stitching, andthus peeling-off of the joints due to remaining air can be reduced.

Further, since the joints apart from each other in the circumferentialdirection are formed in the molded inner liner and unvulcanized rubbersheet such as a carcass ply, even if the joint of the carcass ply peelsoff, the peel-off portion is reinforced by the inner liner, and thusdamage and breakage of a product tire is alleviated.

In particular, in the present invention, when the inner liner iscomposed of a composite layer of the first layer disposed on the innerside of the tire and having a thickness of 0.05 mm to 0.6 mm and thesecond layer disposed on the side of the unvulcanized rubber sheet andhaving a thickness of 0.01 mm to 0.3 mm, adhesive strength with rubberof the adjacent carcass ply is enhanced. In addition, the inner linerhas a high reinforcing effect when the joint of the carcass ply peelsoff, and the carcass ply has a high reinforcing effect when the joint ofthe inner liner peels off.

As for a fourth effect of the present invention, the inner liner isformed of a composite body in the present invention. The inner liner andthe unvulcanized rubber sheet are laminated with being displaced fromeach other in the width direction, then the laminate is wound on thedrum over its entire circumference with the inner liner being disposedon the inner surface side, and the end portions of the inner liner andthe end portions of the unvulcanized rubber sheet are each joined at thepositions apart from each other in the circumferential direction of thedrum. Thereby, a step difference in thickness at a joint of the innerliner and a joint of the unvulcanized rubber sheet can be alleviated. Inaddition, air at these joints can be reliably removed by stitching, andthus peeling-off of the joints due to remaining air can be reduced.

Further, since the joints apart from each other in the circumferentialdirection are formed in the molded inner liner and unvulcanized rubbersheet such as a carcass ply, even if the joint of the carcass ply peelsoff, the peel-off portion is reinforced by the inner liner, and thusdamage and breakage of a product tire is alleviated.

In the present invention, since the inner liner is composed of acomposite body of the first layer mainly composed of an SIBS and thesecond layer made of a styrene-based thermoplastic elastomer, and atackifier is mixed in one of the layers, vulcanization adhesion betweenthe first layer and the second layer can be improved. As a result,adhesiveness between the first layer and the carcass ply is alsoenhanced, and occurrence of an air-in phenomenon between the first layerand the carcass ply, between the first layer and the second layer, andbetween the carcass ply and the second layer can be prevented, improvingtire durability performance. Further, since the second layer is blendedwith an SIBS, adhesiveness with the first layer is improved, and thusadhesion among the first layer, the second layer, and the carcass plycan be further enhanced.

As for a fifth effect of the present invention, in the manufacturingmethod in accordance with the present invention, the inner liner made ofan isobutylene-based modified copolymer and the unvulcanized rubbersheet are laminated with being displaced from each other in the widthdirection, and the laminate is wound on the drum over its entirecircumference with the inner liner being disposed on the inner surfaceside. Then, the end portions of the inner liner and the end portions ofthe unvulcanized rubber sheet are each joined at the positions apartfrom each other in the circumferential direction of the drum. Thereby, astep difference in thickness at a joint of the inner liner and a jointof the unvulcanized rubber sheet can be alleviated. In addition, air atthese joints can be reliably removed by stitching, and thus peeling-offof the joints due to remaining air can be reduced.

Further, since the joints apart from each other in the circumferentialdirection are formed in the molded inner liner and unvulcanized rubbersheet such as a carcass ply, even if the joint of the carcass ply peelsoff, the peel-off portion is reinforced by the inner liner, and thusdamage and breakage of a product tire is alleviated.

In addition, the inner liner has a high reinforcing effect when thejoint of the carcass ply peels off, and the carcass ply has a highreinforcing effect when the joint of the inner liner peels off.

As for a sixth effect of the present invention, the inner liner iscomposed of a composite layer of the first layer made of an SIBSmodified copolymer and the second layer containing an SIS or an SIB inthe present invention. The inner liner and the unvulcanized rubber sheetare laminated with being displaced from each other in the widthdirection, then the laminate is wound on the drum over its entirecircumference with the inner liner being disposed on the inner surfaceside, and the end portions of the inner liner and the end portions ofthe unvulcanized rubber sheet are each joined at the positions apartfrom each other in the circumferential direction of the drum. Thereby, astep difference in thickness at a joint of the inner liner and a jointof the unvulcanized rubber sheet can be alleviated. In addition, air atthese joints can be reliably removed by stitching, and thus peeling-offof the joints due to remaining air can be reduced.

Further, since the joints apart from each other in the circumferentialdirection are formed in the molded inner liner and unvulcanized rubbersheet such as a carcass ply, even if the joint of the carcass ply peelsoff, the peel-off portion is reinforced by the inner liner, and thusdamage and breakage of a product tire is alleviated.

In addition, the inner liner has a high reinforcing effect when thejoint of the carcass ply peels off, and the carcass ply has a highreinforcing effect when the joint of the inner liner peels off.

In particular, flex crack growth, durability driving index, anduniformity are improved by adopting the manufacturing method describedabove as well as using a laminated structure of the first layer and thesecond layer for the inner liner, using an SIBS modified copolymer forthe first layer, and using one of an SIS and an SIB for the secondlayer. Further, weather resistance is also improved by blending anultraviolet absorber, an antioxidant in the first layer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing an assembly step.

FIG. 2 is a perspective view schematically showing the assembly step.

FIG. 3 is a schematic view showing a cutting step.

FIG. 4( a) is a cross sectional view of a laminate, and FIG. 4( b) is aschematic view showing the state where the laminate is wound on a drum.

FIG. 5 is a schematic view showing the cutting step.

FIG. 6( a) is a cross sectional view of a laminate, and FIG. 6( b) is aschematic view showing the state where the laminate is wound on thedrum.

FIG. 7 is a schematic view of a conventional method for molding an innerliner.

FIG. 8 is a schematic cross sectional view of a pneumatic tire.

FIG. 9 is a schematic cross sectional view of a polymer laminate.

DESCRIPTION OF EMBODIMENTS

The present invention is directed to a method for manufacturing apneumatic tire having an inner liner on an inner side of the tire, themanufacturing method being performed through the following step ofmolding a green tire including:

(a) an assembly step of bonding the inner liner and an unvulcanizedrubber sheet with end portions thereof in a width direction beingdisplaced from each other in the range of 50 mm to 500 mm in the widthdirection to manufacture a laminate;

(b) a cutting step of cutting the laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and

(c) a joining step of winding the cut sheet on entire circumference ofthe drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining the end portions of the inner liner andjoining the end portions of the unvulcanized rubber sheet such thatpositions of the joined end portions are displaced by a constantdistance.

Here, the method for manufacturing the pneumatic tire in accordance withthe present invention will be described with reference to the drawings.

Embodiment 1-1 Assembly Step

FIG. 1 is a schematic lateral view showing the assembly step, and FIG. 2is a schematic perspective view showing the assembly step. In FIGS. 1and 2, a film-like inner liner 2 covered with exfoliate paper is fedfrom a storage roll R1 via a first drive roller R2 in a directionindicated by an arrow, and is separated from the exfoliate paper atpeel-off rollers R3, R4. Then, inner liner 2 is fed to a pair ofcalender rolls R7.

On the other hand, an unvulcanized rubber sheet 3 is fed via a seconddrive roller R6 to the pair of calender rolls R7. Inner liner 2 andunvulcanized rubber sheet 3 are bonded by the pair of calender rolls R7to manufacture a laminate 1. Laminate 1 is taken up by a take-up roll R8for temporary storage, or is continuously fed to the subsequent cuttingstep. Here, inner liner 2 and unvulcanized rubber sheet 3 having asubstantially identical width are used, and positions of their both endsare displaced from each other to form a displaced distance L.

Here, displaced distance L is adjusted in the range of 50 mm to 500 mm,preferably in the range of 100 mm to 300 mm. If displaced distance L isless than 50 mm, a space between a joint of the unvulcanized rubbersheet and a joint of the inner liner is small, and adhesion failure atthe joints is likely to occur. On the other hand, if displaced distanceL is more than 500 mm, it is difficult to mold a tire on a drum.

The inner liner is composed of a composite layer of a first layer madeof a styrene-isobutylene-styrene block copolymer and having a thicknessof 0.05 mm to 0.6 mm, and a second layer disposed on a side of theunvulcanized rubber sheet, made of a thermoplastic elastomer, and havinga thickness of 0.01 mm to 0.3 mm. Further, the width of the inner lineris adjusted depending on the size of the tire.

In the present invention, since the inner liner and the unvulcanizedrubber sheet are pressure-bonded using the rolls, they can be closelybonded reliably with no air left therebetween, and they can be bondedefficiently and with good productivity.

<Cutting Step>

FIG. 3 is a schematic perspective view showing the cutting step.Laminate 1 is fed from take-up roll R8, or continuously from theassembly step, to a cutter by a belt conveyer. Laminate 1 is cut to havea predetermined length in a longitudinal direction in accordance withthe size of the tire to manufacture a cut sheet 4. A conventionaltechnique such as cutting with a knife can be adopted to cut thelaminate. A cutting direction of cut sheet 4 corresponds to acircumferential direction of a drum, and a cutting length thereof in thelongitudinal direction corresponds to a width direction of drum 5.Further, the length of the inner liner is adjusted as appropriatedepending on the size of the tire.

<Joining Step>

FIG. 4 is a schematic view showing the joining step for the laminate, inwhich FIG. 4( a) is a cross sectional view of cut sheet 4, and FIG. 4(b) is a schematic view showing a method for winding cut sheet 4 on drum5. The laminate is wound such that inner liner 2 is adjacent to thesurface of drum 5. Here, a position where end portions 2 a, 2 b of theinner liner are joined each other to form the joint and a position whereend portions 3 a, 3 b of the unvulcanized rubber sheet are joined eachother to form the joint are offset from each other.

<Tire Molding/Vulcanization Step>

As described above, in the joining step, the laminate of the inner linerand an unvulcanized carcass ply is manufactured and formed into acylindrical shape on the drum. After the joining step, both end portionsof the laminate located at both ends of the drum are folded back aroundbead cores, and thereafter a central portion of the laminate made of theinner liner and the unvulcanized carcass ply is expanded and deformedwhile narrowing a space between the bead cores. In association with thisoperation, a belt member, tread rubber, and the like are bonded to thecentral portion of the laminate, and other rubber members such as a sidewall, a bead apex, and the like are also bonded to mold a green tire.The green tire molded as described above is introduced into a mold andvulcanized by a conventional method to obtain a product tire.

<Inner Liner>

In the present embodiment, the inner liner is composed of the firstlayer disposed on the inner side of the tire, and the second layerdisposed in contact with a rubber layer of the carcass ply.

<First Layer>

The first layer is composed of a thermoplastic elastomer compositioncontaining 0.1 to 50 parts by mass of an organic derivative of a claymineral relative to 100 parts by mass of a thermoplastic elastomermixture containing 60 to 99% by mass of a styrene-isobutylene-styreneblock copolymer (hereinafter also referred to as an “SIBS”) and 1 to 40%by mass of a polyamide-based polymer that contains polyamide in amolecular chain and has a Shore D hardness of 70 or less.

(SIBS)

The first layer is made of a thermoplastic elastomer composition mainlycomposed of a styrene-isobutylene-styrene block copolymer (SIBS). Sincethe SIBS is derived from an isobutylene block, a polymer film made ofthe SIBS has excellent air permeation resistance. Therefore, when apolymer made of the SIBS is used for the inner liner, a pneumatic tirehaving excellent air permeation resistance can be obtained.

Further, the SIBS has excellent durability since a molecular structureother than those of aromatic molecules is completely saturated andtherefore deterioration and hardening are suppressed. Therefore, when apolymer film made of the SIBS is used for the inner liner, a pneumatictire having excellent durability can be obtained.

When a pneumatic tire is manufactured by using a polymer film made ofthe SIBS for the inner liner, air permeation resistance can be ensured.Therefore, it is not necessary to use a halogenated rubber having a highspecific gravity such as halogenated butyl rubber, which has beenconventionally used to impart air permeation resistance, and even if thehalogenated rubber is used, the amount of use can be reduced. Thisenables weight saving of the tire and improves fuel efficiency.

Although there is no particular limitation on the molecular weight ofthe SIBS, the weight-average molecular weight obtained by GPCmeasurement is preferably 50,000 to 400,000 in view of fluidity,workability, rubber elasticity, and the like. When the weight-averagemolecular weight is less than 50,000, tensile strength and tensileelongation may decrease. When the weight-average molecular weight ismore than 400,000, extrusion moldability may deteriorate. Therefore,both the cases are not preferred. In the SIBS, in view of furtherimproving air permeation resistance and durability, the content of astyrene component in the SIBS is 10 to 30% by mass, preferably 14 to 23%by mass.

In the SIBS as a copolymer, the polymerization degree of each block ispreferably about 10,000 to 150,000 for isobutylene and about 5,000 to30,000 for styrene, in view of rubber elasticity and handling (when thepolymerization degree is less than 10,000, the SIBS becomes a liquid).

The SIBS can be obtained by a conventional living cationicpolymerization method for a vinyl-based compound. For example, JapanesePatent Laying-Open No. 62-048704 and Japanese Patent Laying-Open No.64-062308 disclose that living cationic polymerization of isobutylenewith other vinyl compounds can be performed, and a polyisobutylene-basedblock copolymer can be manufactured by using isobutylene and othercompounds as the vinyl compounds.

(Polyamide-Based Polymer)

In the first layer, the content of the polyamide-based polymer in thethermoplastic elastomer mixture is set to 1 to 40% by mass. Since thecontent of the polyamide-based polymer is 40% by mass or less, a polymermixture that has both durability and adhesiveness is obtained. Further,when the SIBS, which can ensure durability and adhesiveness and hasexcellent air permeation resistance, is used together with anethylene-vinyl alcohol copolymer, the content of the polyamide-basedpolymer is preferably set to 3 to 20% by mass.

The polyamide-based polymer is a polyamide-based polymer having a ShoreD hardness of 70 or less. A Shore D hardness exceeding 70 results inpoor cracking properties when the tire flexes and moves. The Shore Dhardness is preferably within a range from 15 to 70, more preferablyfrom 18 to 70, further preferably from 20 to 70, and particularlypreferably from 25 to 70. The polyamide-based polymer preferablycontains more than or equal to 50% by mass of a polyetheramide elastomerhaving a structure represented by the following formula (I).

Here, the polyetheramide elastomer is preferably a block copolymercomposed of a polyamide component and a polyether component, obtained bypolymerizing a triblock polyether diamine compound (A) represented byformula (I), a polyamide-forming monomer (B), and a dicarboxylic acidcompound (C):

(where a and b represent 1 to 20, and c represents 4 to 50).

The polyamide-forming monomer (B) is preferably represented by formula(II) or (III):

[Formula 2]

H₂N—R¹—COOH  (II)

(where R¹ represents a linking group containing a hydrocarbon chain);

(where R² represents a linking group containing a hydrocarbon chain).

The dicarboxylic acid compound (C) is preferably represented by thefollowing formula (IV) or an aliphatic dicarboxylic acid compound and/oran alicyclic dicarboxylic acid compound:

(where R³ represents a linking group containing a hydrocarbon chain, andy represents 0 or 1).

When the polyamide-based polymer is a polyamide-based polymer having ahard segment derived from a polyamide component and a soft segmentderived from a polyether component, it shows low crystallinity.Therefore, it is possible to obtain a polyamide-based polymer that has ahigh elongation at break (EB) and shows flexibility within a temperaturerange from a low temperature to a high temperature.

Further, the polyamide-based polymer can exhibit an excellent effect inadhesiveness with an adjacent rubber, since fluidity improves at a tirevulcanization temperature (140 to 180° C.) and wettability with anuneven surface improves.

As the polyamide-based polymer, a known polyamide-based polymer can beused. As the polyamide-based polymer, for example, an elastomer composedof a polyamide block made of at least one aliphatic nylon selected fromnylon 6, nylon 66, nylon 11, and nylon 12, and at least one polyetherblock selected from polyoxyethylene, polyoxypropylene, andpolyoxybutylene can be used.

<Ethylene-Vinyl Alcohol Copolymer>

The thermoplastic elastomer composition of the first layer preferablycontains 15 to 40% by mass of an ethylene-vinyl alcohol copolymer in apolymer component. Since the content of the ethylene-vinyl alcoholcopolymer is 15% by mass or more, gas barrier property of thethermoplastic elastomer composition is ensured. Since the content is 40%by mass or less, kneadability of the thermoplastic elastomer compositionduring fabrication is ensured, and basic performance such as mechanicalstrength in an inner liner layer of the tire is also ensured. Thecontent is more preferably 20% by mass or more, and still morepreferably 25% by mass or more. Furthermore, in view of durability ofthe tire, the content is more preferably 30% by mass or less. Theethylene-vinyl alcohol copolymer is represented by the following generalformula (V):

(where m and n each independently represent 1 to 100, and X is from 1 to1,000).

Compatibility with other components in the polymer mixture issatisfactorily imparted by an ethylene-derived moiety of theethylene-vinyl alcohol copolymer, and the ethylene-vinyl alcoholcopolymer can exist in a fine dispersion size in the polymercomposition. On the other hand, the ethylene-vinyl alcohol copolymer hassatisfactory gas barrier property due to contribution of a vinylalcohol-derived moiety. Specifically, in the present invention, sincethe ethylene-vinyl alcohol copolymer having excellent gas barrierproperty is dispersed in the form of islands in a fine size in thethermoplastic elastomer composition, satisfactory gas barrier propertyis exhibited even when a thin inner liner layer of a tire is formed.Thereby, weight saving of the tire can be achieved, and the effect ofimproving fuel efficiency is obtained.

In the general formula (V), m and n are set to 1 or more to constitutethe ethylene-vinyl alcohol copolymer. On the other hand, since m and nare each 100 or less, an ethylene-vinyl alcohol copolymer that has bothcompatibility with other components in the polymer mixture and gasbarrier property is obtained. Since compatibility with other componentsin the polymer mixture becomes more satisfactory, m is more preferablyset to 5 or more. Further, since gas barrier property becomes moresatisfactory, n is more preferably set to 5 or more. On the other hand,since it is hard to fail to exhibit gas barrier property due to thevinyl alcohol-derived moiety, m is preferably set to 95 or less, andmore preferably 80 or less. Further, since it is hard to fail to exhibitsatisfactory compatibility with the polymer mixture due to theethylene-derived moiety, n is preferably set to 95 or less, and morepreferably 80 or less.

In the general formula (V), x is set to 1 or more to constitute theethylene-vinyl alcohol copolymer. On the other hand, since x is 1,000 orless, kneadability of the polymer composition during fabrication isensured, and a polymer composition containing an ethylene-vinyl alcoholcopolymer dispersed uniformly therein is obtained. Since compatibilitywith other components in the polymer mixture and gas barrier propertyare satisfactorily exhibited, x is more preferably set to 10 or more. Inview of satisfactory kneadability, x is still more preferably set to 500or less, and even more preferably 100 or less.

The ethylene-vinyl alcohol copolymer represented by the general formula(V) may be contained in the polymer composition, in the state of beingcopolymerized with other components. In this case, the content of theethylene-vinyl alcohol copolymer means the content of the structuremoiety represented by the general formula (V). The molecular structureof the ethylene-vinyl alcohol copolymer can be confirmed, for example,by an infrared absorption spectrum (IR) and a nuclear magnetic resonancespectrum (NMR).

<Polymer Mixture>

In the present embodiment, the thermoplastic elastomer composition canbe blended with other polymers in a range of 20% by mass or less, inaddition to the SIBS, the polyamide-based polymer, the ethylene-vinylalcohol copolymer, as the polymer component. For example, thethermoplastic elastomer composition can be blended with PET, chlorobutylrubber, natural rubber, ethylene-propylene-diene terpolymer (EPDM),styrene-butadiene rubber (SBR), butadiene rubber, isoprene rubber, butylrubber, halogenated butyl rubber, and acrylonitrile-butadiene rubber(NBR).

<Organic Derivative of a Clay Mineral>

The first layer of the laminate contains 0.1 to 50 parts by mass of anorganic derivative of a clay mineral relative to 100 parts by mass ofthe polymer component of the thermoplastic elastomer composition. Theorganic derivative of a clay mineral is a layered clay mineral obtainedby intercalating an organic compound. By intercalating the organiccompound between layers of the layered clay mineral, interlayerexpansion occurs and dispersibility in the polymer is improved.

The layered clay mineral is a kind of layered silicate minerals, and hasa crystal structure in which three layers of a silicic acid tetrahedronlayer, an alumina octahedron layer, and a silicic acid tetrahedron layerare laminated, and the unit layer is in the form of a very thin platehaving a thickness of about 10 Å (1 nm) and a spread of 0.1 to 1 μm.

Typical examples of the layered clay mineral include montmorillonite.Montmorillonite has an insufficient positive charge since a portion ofA1 atoms as a central atom of an alumina octahedron layer in a crystalstructure may be substituted with Mg atoms, and thus each crystal layeritself is negatively charged, but the insufficient charge is alleviatedby interposing cations such as Na⁺, K⁺, Ca²⁺, and Mg²⁺ between thecrystal layers, resulting in a stable state. Therefore, montmorilloniteis present in a state where a number of crystal layers are laminated.

When water is brought into contact with a surface of a plate crystallayer of montmorillonite, water molecules are hydrated with interlaminarexchangeable cations and interlayer expansion occurs. Further, byintercalating an organic compound between layers utilizing cationexchangeability of montmorillonite, interlayer expansion occurs and thusdispersibility in an organic solvent or a polymer is improved.

Examples of the layered clay mineral include phyllosilicates, forexample, smectite-based clays such as montmorillonite (particularlysodium montmorillonite, magnesium montmorillonite, and calciummontmorillonite), bentonite, kaolinite, nonlite, beidellite,volchonskoite, hectorite, saponite, sauconite, sobockite, stevensite,svinfordite, and vermiculite; mica minerals such as illite andillite/smectite mixtures (mixtures of rectorite, tarosovite, ledikite,and the clay compounds described above, and illite), or attapulgite anda sepiolitehydrotalcite-based layered compound. Of these layered clayminerals, a smectite-based clay is preferred, and amontmorillonite-based clay is particularly preferred. Bentonitecontaining a smectite-based clay mineral may also be used. These layeredclay minerals are usually obtained by collecting a natural mineral andsubjecting the mineral to a predetermined purification operation. Thesesynthetic clays can be used without any distinction.

Examples of the organic compound that can be used as an intercalantinclude an organic compound having an easily ionizable polar group inthe molecule. It is considered that the organic compound having a polargroup causes a strong interaction with a surface of a layer coated withnegative ions such as oxygen ions of a smectite-based clay mineral, andintercalates between layers of the layered clay mineral, resulting ininterlayer expansion.

The organic compound is preferably a compound which has an alkyl grouphaving 6 or more carbon atoms, and has an ionizable polar group at theend. Examples thereof include those having a hydroxyl group or acarboxyl group, aldehydes, amines, amides, or quaternary ammonium salts.

Examples of the organic compound having a hydroxyl group includealiphatic alcohols such as octyl alcohol and nonyl alcohol; alcoholssubstituted with an alkyl group, such as aromatic alcohol; and phenols.

Examples of the organic compound having a carboxyl group include linearaliphatic acids such as stearic acid, palmitic acid, and lauric acid;linear alkenoic acids such as oleic acid; dienoic acids such aslinolelaidic acid; and polyunsaturated aliphatic acids such as trienonicacid.

Examples of aldehydes include hexylaldehyde. Examples of amines oramides include polar organic compounds having one or more amines oramides, such as alkylamines, aminocycloalkanes and aminocycloalkanesubstituted compounds, cyclic aliphatic diamines, aliphatic amines,alkylaromatic amines, alkyldiarylamines, and aliphatic amides, and alsoinclude primary, secondary, and/or tertiary amines or amides. Of these,alkylamines, aliphatic amines, alkylaromatic amines, andalkyldiarylamines are preferred. These organic compounds can be usedalone, or two or more types thereof can be used in combination.

Examples of amines include primary amines such as 1-hexylamine,1-heptylamine, 1-octylamine, 1-nonylamine, 1-dodecylamine,1-hexadecylamine, 1-octadecylamine, and oleylamine; secondary aminessuch as di-n-dodecylamine, di-n-hexadecylamine, and di-n-octadecylamine;tertiary amines such as dimethyl-n-octylamine, dimethyl-n-decylamine,dimethyl-n-tetradecylamine, dimethyl-n-hexadecylamine,dimethyl-n-octadecylamine, and dimethyloleylamine; and aliphatic aminessuch as di-n-decylmethylamine di(coco alkyl)methylamine,tri-n-octylamine, tri-n-decylamine, and tri-n-hexadecylamine.

Examples of amides include hexylamide, heptylamide, octylamide,nonylamide, lauramide, myristamide, palmitamide, steramide, palmiamide,oleamide, and linoleamide.

It is also possible to use, as the organic compound having a polargroup, those having a nitrile group or a lactam group, pyridines,esters, surfactants, ethers, and the like.

Examples of the quaternary ammonium salt include adimethyldistearylammonium salt, a trimethylstearylammonium salt,dimethyldioctadecylammonium, dimethylbenzyloctadecylammonium, andtrimethyloctadecylammonium.

As a method of intercalating an organic compound into a layered claymineral, a known method can be employed. For example, there is a methodin which, in order to bring a montmorillonite-based clay mineral intocontact with an organic compound, a layered clay mineral is impregnatedwith water in the amount of about 10% by mass of the layered claymineral to 20 times thereof in advance, and then the organic compound isbrought into contact with the montmorillonite-based clay mineral toobtain an organic derivative of a clay mineral. The cation exchangeamount of the organic compound in the organic derivative of a claymineral is preferably from 50 to 200 meg/100 g.

The blending quantity of the organic derivative of a clay mineral is 0.1to 50% by mass, and more preferably 0.5 to 30 parts by mass, relative to100 parts by mass of the polymer mixture. When the blending quantity ofthe organic derivative of a clay mineral is less than 0.1 parts by mass,air permeability of the polymer composition and its tensilecharacteristics at high temperature deteriorate. In contrast, when theblending quantity of the organic derivative of a clay mineral is morethan 50 parts by mass, the hardness of the polymer compositionexcessively increases and thus flex fatigue properties deteriorate.

<Other Compounding Agents>

The thermoplastic elastomer composition in the present embodiment can beblended with various compounding agents and additives which are blendedinto a common rubber composition, such as other reinforcing agents,vulcanization agents, vulcanization accelerators, various oils, ageinhibitors, softeners, plasticizers, and coupling agents. The content ofthese compounding agents and additives can also be set to a commonamount.

(Thickness of First Layer)

The thickness of the first layer made of the SIBS is 0.05 to 0.6 mm.When the thickness of the first layer is less than 0.05 mm, the firstlayer may be broken by a pressing pressure during vulcanization of agreen tire in which a polymer laminate is used as the inner liner, andthus an air leak phenomenon may occur in the resultant tire. On theother hand, when the thickness of the first layer is more than 0.6 mm,tire weight increases and fuel efficiency performance deteriorates. Thethickness of the first layer is preferably 0.05 to 0.4 mm. The firstlayer can be obtained by forming the SIBS into a film by a conventionalmethod of forming a thermoplastic resin or a thermoplastic elastomerinto a film, such as extrusion molding or calender molding.

<Second Layer>

In the present embodiment, the second layer is composed of athermoplastic elastomer, in particular a styrene-based thermoplasticelastomer composition. Here, the styrene-based thermoplastic elastomerrefers to a copolymer containing a styrene block as a hard segment.Examples thereof include a styrene-isoprene-styrene block copolymer(hereinafter also referred to as an “SIS”), a styrene-isobutylene blockcopolymer (hereinafter also referred to as an “SIB”), astyrene-butadiene-styrene block copolymer (hereinafter also referred toas an “SBS”), a styrene-isobutylene-styrene block copolymer (hereinafteralso referred to as an “SIBS”), a styrene-ethylene-butene-styrene blockcopolymer (hereinafter also referred to as an “SEBS”), astyrene-ethylene-propylene-styrene block copolymer (hereinafter alsoreferred to as an “SEPS”), a styrene-ethylene-ethylene-propylene-styreneblock copolymer (hereinafter also referred to as an “SEEPS”), and astyrene-butadiene-butylene-styrene block copolymer (hereinafter alsoreferred to as an “SBBS”).

Further, the styrene-based thermoplastic elastomer may have an epoxygroup in its molecular structure, and for example an epoxy-modifiedstyrene-butadiene-styrene copolymer (epoxidized SBS) such as EpofriendA1020 manufactured by Daicel Chemical Industries, Ltd. (having aweight-average molecular weight of 100,000 and an epoxy equivalent of500) can be used.

Of the styrene-based thermoplastic elastomers used for the second layer,the SIS and the SIB are particularly suitable. Since an isoprene blockof the SIS is a soft segment, a polymer film made of the SIS is easilyvulcanization-bonded with a rubber component. Therefore, when thepolymer film made of the SIS is used for the inner liner, the innerliner is excellent in adhesiveness with the rubber layer of the carcassply, for example, and thus a pneumatic tire excellent in durability canbe obtained.

Although there is no particular limitation on the molecular weight ofthe SIS, the weight-average molecular weight obtained by the GPCmeasurement is preferably 100,000 to 290,000 in view of rubberelasticity and moldability. When the weight-average molecular weight isless than 100,000, tensile strength may decrease. When theweight-average molecular weight is more than 290,000, extrusionmoldability may deteriorate. Therefore, both the cases are notpreferred. The content of a styrene component in the SIS is preferably10 to 30% by mass in view of tackiness, adhesiveness, and rubberelasticity.

In the present invention, the polymerization degree of each block in theSIS is preferably about 500 to 5,000 for isoprene and about 50 to 1,500for styrene, in view of rubber elasticity and handling.

The SIS can be obtained by a conventional polymerization method for avinyl-based compound, and can be obtained, for example, by the livingcationic polymerization method. An SIS layer can be obtained by formingthe SIS into a film by a conventional method of forming a thermoplasticresin or a thermoplastic elastomer into a film, such as extrusionmolding or calender molding.

Since an isobutylene block of the styrene-isobutylene block copolymer(SIB) is a soft segment, a polymer film made of the SIB is easilyvulcanization-bonded with a rubber component. Therefore, when thepolymer film made of the SIB is used for the inner liner, the innerliner is excellent in adhesiveness with an adjacent rubber constitutinga carcass or an insulation, for example, and thus a pneumatic tireexcellent in durability can be obtained.

It is preferable to use a linear SIB in view of rubber elasticity andadhesiveness. Although there is no particular limitation on themolecular weight of the SIB, the weight-average molecular weightobtained by the GPC measurement is preferably 40,000 to 120,000 in viewof rubber elasticity and moldability. When the weight-average molecularweight is less than 40,000, tensile strength may decrease. When theweight-average molecular weight is more than 120,000, extrusionmoldability may deteriorate. Therefore, both the cases are notpreferred.

The content of a styrene component in the SIB is preferably 10 to 35% bymass in view of tackiness, adhesiveness, and rubber elasticity. In thepresent invention, the polymerization degree of each block in the SIB ispreferably about 300 to 3,000 for isobutylene and about 10 to 1,500 forstyrene, in view of rubber elasticity and handling.

The SIB can be obtained by a conventional living polymerization methodfor a vinyl-based compound. For example, methylcyclohexane, n-butylchloride, and cumyl chloride are charged in a stirrer, cooled to −70° C.and thereafter reacted for 2 hours, and then the reaction is terminatedby adding a large amount of methanol, and the reaction product isvacuum-dried at 60° C. Thereby, the SIB can be manufactured.

The second layer can be molded, for example, by subjecting the SIB to aconventional method of forming a styrene-based thermoplastic elastomerinto a film, such as extrusion molding or calender molding. Thethickness of the second layer is preferably 0.01 mm to 0.3 mm. Here,when the second layer is made of a plurality of layers, the thickness ofthe second layer refers to the total thickness of these layers. When thethickness of the second layer is less than 0.01 mm, the second layer maybe broken by a pressing pressure during vulcanization of the green tirein which the polymer laminate is used as the inner liner, and thusvulcanization adhesive strength may be reduced. On the other hand, whenthe thickness of the second layer is more than 0.3 mm, tire weight mayincrease and fuel efficiency performance may deteriorate.

<Polymer Laminate>

In the present embodiment, a polymer laminate composed of a compositelayer of the first layer and the second layer is used as the innerlayer. Here, the first layer and the second layer are thermoplasticelastomer compositions, and are in a softened state in the mold at avulcanization temperature, for example 150° C. to 180° C. The softenedstate refers to an intermediate state between a solid and a liquid withimproved molecular mobility. Further, since a thermoplastic elastomercomposition in the softened state has an improved reactivity than in thesolid state, it adheres to or is bonded with an adjacent member.Accordingly, in order to manufacture a tire, a cooling step is requiredto prevent a change in the shape of a thermoplastic elastomer and itsadhesion or fusion to the adjacent member. In the cooling step, theinside of a bladder portion is cooled rapidly to 50 to 120° C. for 10 to300 seconds after vulcanization of the tire. As a cooling medium, atleast one selected from air, steam, water, and oil is used. By adoptingsuch a cooling step, a thin inner liner in the range of 0.05 to 0.6 mmcan be formed as the inner liner.

Embodiment 1-2

In Embodiment 1-2, inner liner 2 has a width W2 formed to be larger thana width W1 of unvulcanized rubber sheet 3.

<Cutting Step>

FIG. 5 is a schematic view showing the cutting step. Laminate 1 is fedfrom take-up roll R8, or continuously from the assembly step, to acutter by a belt conveyer. Laminate 1 is cut to have a predeterminedlength in the longitudinal direction in accordance with the size of thetire to manufacture cut sheet 4. A conventional technique such ascutting with a knife can be adopted to cut the laminate. The cuttingdirection of cut sheet 4 corresponds to the circumferential direction ofthe drum, and the cutting length thereof in the longitudinal directioncorresponds to the width direction of drum 5.

<Joining Step>

FIG. 6( a) is a cross sectional view of the laminate, and FIG. 6( b) isa schematic view showing the joining step of winding the laminate on thedrum. Here, the laminate is wound such that inner liner 2 is on and incontact with drum 5, and end portions 2 a, 2 b thereof are overlapped toform a joint. Thereon, end portions 3 a, 3 b of unvulcanized rubbersheet 3 such as an insulation are joined using an unvulcanized rubberpiece 6. In this case, two joints are formed at positions that areoffset from the position of the joint of the inner liner.

<Structure of Tire>

A pneumatic tire having an inner liner on an inner side of the tire inaccordance with Embodiments 1-1, 1-2 will be described with reference tothe drawings. FIG. 8 is a schematic cross sectional view of the righthalf of the pneumatic tire. In the drawing, a pneumatic tire 11 has atread part 12, and a sidewall part 13 and a bead part 14 forming atoroidal shape from both ends of the tread part. Further, a bead core 15is embedded in bead part 14. Also provided are a carcass ply 16 arrangedto extend from one bead part 14 to the other bead part with each of bothends being folded back around bead core 15 and locked, and a belt layer17 composed of at least two plies on an outer side of carcass ply 16 ata crown part.

The two plies of belt layer 17, each being usually made of a steel cordor a cord of aramid fiber or the like, are arranged so that the cordsintersect with each other between the plies and each form an angle ofusually 5 to 30° with respect to a tire circumferential direction. Atopping rubber layer can be provided on an outer side of each of bothends of the belt layer to reduce peeling-off at the both ends of thebelt layer. Regarding the carcass ply, organic fiber cords made ofpolyester, nylon, aramid or the like are arranged at an angle of about90° with respect to the tire circumferential direction, and a bead apex18 extending from the top end of bead core 15 toward the sidewall isdisposed in a region surrounded by the carcass ply and the folded partthereof. An inner liner 19 extending from one bead part 14 to the otherbead part 14 is disposed on a tire radial inner side of carcass ply 16.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be specifically shown in FIG. 9.In FIG. 9( a), a polymer laminate PL is composed of a first layer PL1and an SIS-based layer (a layer mainly composed of the SIS) PL2 as asecond layer. When polymer laminate PL is used as the inner liner of thepneumatic tire, if SIS-based layer PL2 is arranged toward a tire radialouter side so as to contact a carcass ply C, adhesive strength betweenSIS-based layer PL2 and carcass C can be enhanced in the tirevulcanization step. Therefore, the resultant pneumatic tire can haveexcellent air permeation resistance and durability, since the innerliner is satisfactorily bonded with a rubber layer of carcass ply C.

In FIG. 9( b), polymer laminate PL is composed of first layer PL1 and anSIB-based layer PL3 as a second layer. When polymer laminate PL is usedas the inner liner of the pneumatic tire, if a surface of SIB-basedlayer PL3 is arranged toward the tire radial outer side so as to contactcarcass ply C, adhesive strength between SIB-based layer PL3 and carcassC can be enhanced in the tire vulcanization step. Therefore, theresultant pneumatic tire can have excellent air permeation resistanceand durability, since the inner liner is satisfactorily bonded with therubber layer of carcass ply C.

In FIG. 9( c), polymer laminate PL is composed of first layer PL1 andSIS-based layer PL2 and SIB-based layer PL3 as a second layer, laminatedin the order listed above. When polymer laminate PL is used as the innerliner of the pneumatic tire, if a surface of SIB-based layer PL3 isarranged toward the tire radial outer side so as to contact carcass plyC, adhesive strength between SIB-based layer PL3 and carcass ply C canbe enhanced in the tire vulcanization step. Therefore, the resultantpneumatic tire can have excellent air permeation resistance anddurability, since the inner liner is satisfactorily bonded with therubber layer of carcass ply C.

In FIG. 9( d), polymer laminate PL is composed of first layer PL1 andSIB-based layer PL3 and SIS-based layer PL2 as a second layer, laminatedin the order listed above. When polymer laminate PL is used as the innerliner of the pneumatic tire, if a surface of SIS-based layer PL2 isarranged toward the tire radial outer side so as to contact carcass plyC, adhesive strength between SIS-based layer PL2 and carcass ply C canbe enhanced in the tire vulcanization step. Therefore, the resultantpneumatic tire can have excellent air permeation resistance anddurability, since the inner liner is satisfactorily bonded with therubber layer of carcass ply C.

<Method for Manufacturing Pneumatic Tire>

The pneumatic tire in accordance with the present embodiment can bemanufactured using an ordinary manufacturing method. An inner liner ismanufactured using polymer laminate PL. The inner liner is used for agreen tire for pneumatic tire 11 and vulcanization-molded together withother members, and thereby the pneumatic tire can be manufactured. Whenpolymer laminate PL is arranged in the green tire, SIS-based layer PL2or SIB-based layer PL3 as the second layer of polymer laminate PL isarranged toward the tire radial outer side so as to contact carcass plyC. With such an arrangement, adhesive strength between SIS-based layerPL2 or SIB-based layer PL3 and the carcass ply can be enhanced in thetire vulcanization step. The resultant pneumatic tire can have excellentair permeation resistance and durability, since the inner liner issatisfactorily bonded with the rubber layer of the carcass ply.

Embodiment 2-1

As the assembly step, the cutting step, the joining step, and the tiremolding/vulcanization step, the same methods as those in Embodiment 1-1can be used.

<Inner Liner>

In the present embodiment, an inner liner is formed of a laminate of afirst layer made of a mixture of an SIBS and a C4 polymer and a secondlayer disposed on a side of an unvulcanized rubber sheet, made of athermoplastic elastomer, and having a thickness of 0.01 mm to 0.3 mm.

<First Layer>

The first layer contains more than or equal to 60% by mass and less thanor equal to 99.5% by mass of a styrene-isobutylene-styrene triblockcopolymer (SIBS) and more than or equal to 0.5% by mass and less than orequal to 40% by mass of a polymer obtained by polymerizing a monomerhaving 4 carbon atoms (hereinafter also referred to as a “C4 polymer”),and has a thickness of more than or equal to 0.05 mm and less than orequal to 0.6 mm.

As the SIBS, the same one as that in Embodiment 1-1 can be used.

(C4 Polymer)

In the first layer, the C4 polymer is mixed with the SIBS. The polymercontains a low molecular weight component, which can improveunvulcanization tack strength and vulcanization adhesive strength of thefirst layer with another polymer sheet or rubber layer without degradingair permeation resistance derived from the SIBS. Therefore, using thefirst layer containing the C4 polymer and the SIBS for an inner linerpart of a tire can improve adhesive strength with a rubber layerconstituting an adjacent carcass or insulation, and prevent an air-inphenomenon between the inner liner and the carcass or between the innerliner and the insulation.

The number-average molecular weight of the polymer obtained bypolymerizing a monomer having 4 carbon atoms obtained by a GPC method ispreferably more than or equal to 300 and less than or equal to 3,000,and more preferably more than or equal to 500 and less than or equal to2,500. The weight-average molecular weight of that polymer obtained bythe GPC method is preferably more than or equal to 700 and less than orequal to 100,000, and more preferably more than or equal to 1,000 andless than or equal to 80,000. The viscosity-average molecular weight ofthat polymer obtained by an FCC method is preferably more than or equalto 20,000 and less than or equal to 70,000, and more preferably morethan or equal to 30,000 and less than or equal to 60,000. Examples ofthe C4 polymer include polybutene, polyisobutylene, and the like.

Polybutene is a copolymer having a molecular structure of long chainhydrocarbon mainly composed of isobutene as a monomer unit, with normalbutene being further used, and obtained by causing them to react witheach other. Hydrogenated polybutene can also be used as polybutene.

Polyisobutylene is a copolymer having a molecular structure of longchain hydrocarbon composed of isobutene as a monomer unit and obtainedby polymerization thereof.

(Mixture of SIBS and C4 Polymer)

The first layer contains more than or equal to 0.5% by mass and lessthan or equal to 40% by mass of the C4 polymer. When the content of theC4 polymer is less than 0.5% by mass, vulcanization adhesive strengthwith the carcass or the insulation may be reduced, and when the contentof the C4 polymer is more than 40% by mass, air permeation resistancemay be reduced, further reducing viscosity, which may causedeterioration in extrusion moldability. The content of the C4 polymer ispreferably more than or equal to 5% by mass and less than or equal to20% by mass. On the other hand, the content of the SIBS in the firstlayer is more than or equal to 60% by mass and less than or equal to99.5% by mass. When the content of the SIBS is less than 60% by mass,air permeation resistance may be reduced, and when the content of theSIBS is more than 99.5% by mass, vulcanization adhesive strength withthe carcass or the insulation may be reduced. Therefore, both the casesare not preferred. The content of the SIBS is more preferably more thanor equal to 80% by mass and less than or equal to 95% by mass.

(Thickness of First Layer)

The thickness of the first layer made of the SIBS is 0.05 to 0.6 mm.When the thickness of the first layer is less than 0.05 mm, the firstlayer may be broken by a pressing pressure during vulcanization of agreen tire in which a polymer laminate is used as the inner liner, andthus an air leak phenomenon may occur in the tire. On the other hand,when the thickness of the first layer is more than 0.6 mm, tire weightincreases and fuel efficiency performance deteriorates.

The first layer can be obtained by forming the SIBS and the C4 polymerinto a film by a conventional method of forming a thermoplastic resin ora thermoplastic elastomer into a film, such as extrusion molding orcalender molding.

<Second Layer>

As the second layer, the same one as that in Embodiment 1-1 can be used.

The second layer can be molded by subjecting an SIB to a conventionalmethod of forming a styrene-based thermoplastic elastomer into a film,such as extrusion molding or calender molding. The thickness of thesecond layer is preferably 0.01 mm to 0.3 mm. When the thickness of thesecond layer is less than 0.01 mm, the second layer may be broken by apressing pressure during vulcanization of the green tire in which thepolymer laminate is used as the inner liner, and thus vulcanizationadhesive strength may be reduced. On the other hand, when the thicknessof the second layer is more than 0.3 mm, tire weight may increase andfuel efficiency performance may deteriorate. The thickness of the secondlayer is more preferably 0.05 to 0.2 mm.

Embodiment 2-2

Embodiment 2-2 is different from Embodiment 2-1 in that inner liner 2has width W2 formed to be larger than width W1 of unvulcanized rubbersheet 3.

As the cutting step and the joining step, the same methods as those inEmbodiment 1-2 can be used.

<Structure of Tire>

The tire manufactured based on Embodiments 2-1, 2-2 can have the samestructure as that in Embodiment 1-1.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be shown in FIG. 9( a). In FIG. 9(a), polymer laminate PL is composed of first layer PL1 and second layerPL2. When polymer laminate PL is used as the inner liner of thepneumatic tire, if second layer PL2 is arranged toward the tire radialouter side so as to contact carcass ply C, adhesive strength betweensecond layer PL2 and carcass C can be enhanced in the tire vulcanizationstep. The resultant pneumatic tire has excellent air permeationresistance and flex crack growth resistance, since the inner liner issatisfactorily bonded with the rubber layer of carcass ply C.

<Method for Manufacturing Pneumatic Tire>

As a method for manufacturing the pneumatic tire in accordance with thepresent invention, a conventional manufacturing method can be used. Aninner liner is manufactured using polymer laminate PL. The inner lineris used for a green tire for pneumatic tire 11 and vulcanization-moldedtogether with other members, and thereby the pneumatic tire ismanufactured. When polymer laminate PL is arranged in the green tire,second layer PL2 of polymer laminate PL is arranged toward the tireradial outer side so as to contact carcass ply C. With such anarrangement, adhesive strength between second layer PL2 and carcass 6can be enhanced in the tire vulcanization step. The resultant pneumatictire has excellent air permeation resistance and flex crack growthresistance, since the inner liner is satisfactorily bonded with therubber layer of carcass ply C.

Embodiment 3-1

As the assembly step, the cutting step, the joining step, and the tiremolding/vulcanization step, the same methods as those in Embodiment 1-1can be used.

<Inner Liner>

In the present embodiment, an inner liner is composed of a sheet of apolymer composition made of a mixture of a styrene-isobutylene-styrenetriblock copolymer (hereinafter also referred to as an “SIBS”) and arubber component. Further, the inner liner can also be composed of acomposite body of a first layer made of the polymer sheet and a secondlayer made of a thermoplastic elastomer composition.

The inner liner is composed of a single layer of a polymer sheet made ofa polymer composition containing a styrene-isobutylene-styrene blockcopolymer and a rubber component, and having a thickness of 0.05 mm to0.6 mm, or alternatively, the inner liner is composed of a compositelayer of a first layer made of the polymer sheet and a second layerdisposed on a side of an unvulcanized rubber sheet, made of athermoplastic elastomer, and having a thickness of 0.01 mm to 0.3 mm.Further, the width of the inner liner is adjusted depending on the sizeof the tire.

<Polymer Composition>

In the present embodiment, the polymer sheet is made of a polymercomposition containing more than or equal to 0.1 parts by mass and lessthan or equal to 5 parts by mass of sulfur relative to 100 parts by massof a polymer component containing more than or equal to 5% by mass andless than or equal to 40% by mass of a styrene-isobutylene-styrenetriblock copolymer (SIBS) and more than or equal to 60% by mass and lessthan or equal to 95% by mass of at least one rubber component selectedfrom the group consisting of natural rubber, isoprene rubber, and butylrubber.

The polymer composition contains an SIBS, a rubber component, andsulfur. When a rubber component and sulfur are added to the SIBS andmixed by heating, the rubber component and sulfur produce avulcanization reaction during mixing by heating to form a sea-islandstructure in which the SIBS serves as a matrix (sea) and the rubbercomponent serves as an island.

The polymer composition having the sea-island structure has airpermeation resistance derived from the matrix phase made of the SIBS.Further, the rubber component constituting the island phase hastackiness before vulcanization with an adjacent member containing arubber component and vulcanization adhesiveness with the adjacent memberbecause of the vulcanization reaction produced with the rubber componentof the adjacent member during mixing by heating. Therefore, the polymersheet made of the polymer composition can have excellent air permeationresistance, and tackiness before vulcanization and vulcanizationadhesiveness with the adjacent member.

As the SIBS, the same one as that in Embodiment 1-1 can be used.

The SIBS content is more than or equal to 5% by mass and less than orequal to 40% by mass in the polymer component of the polymercomposition. When the SIBS content is less than 5% by mass, airpermeation resistance of the polymer sheet may be reduced. On the otherhand, when the SIBS content is more than 40% by mass, vulcanizationadhesiveness with the adjacent member may be insufficient. The SIBScontent is preferably more than or equal to 10% by mass and less than orequal to 30% by mass in the polymer component, from the viewpoint ofensuring air permeation resistance.

(Rubber Component)

The polymer composition constituting the polymer sheet for the innerliner contains a rubber component. The rubber component can provide thepolymer composition with tackiness before vulcanization with an adjacentmember containing a rubber component. Further, because of thevulcanization reaction with sulfur, the rubber component can provide thepolymer composition with vulcanization adhesiveness with an adjacentmember such as a carcass or an insulation. The rubber component containsat least one selected from the group consisting of natural rubber,isoprene rubber, and butyl rubber, and particularly preferably containsnatural rubber in view of breaking strength and adhesiveness.

The content of the rubber component is more than or equal to 60% by massand less than or equal to 95% by mass in the polymer component of thepolymer composition. When the content of the rubber component is lessthan 60% by mass, the viscosity of the polymer composition increases tocause extrusion moldability to deteriorate, so that when fabricating apolymer sheet, the polymer sheet cannot be made thin. On the other hand,when the content of the rubber component is more than 95% by mass, airpermeation resistance of the polymer sheet may be reduced. The contentof the rubber component is preferably more than or equal to 70% by massand less than or equal to 90% by mass in the polymer component in viewof tackiness before vulcanization and vulcanization adhesiveness.

(Sulfur)

For the polymer composition, sulfur commonly used can be used, and it ispreferable to use insoluble sulfur. Here, insoluble sulfur refers tosulfur obtained by heating and rapidly cooling natural sulfur S₈, andpolymerizing it so as to become Sx (x=100,000 to 300,000). The use ofinsoluble sulfur can prevent blooming that would usually occur whensulfur is used as a rubber vulcanization agent.

The sulfur content is more than or equal to 0.1 parts by mass and lessthan or equal to 5 parts by mass relative to 100 parts by mass of thepolymer component. When the sulfur content is less than 0.1 parts bymass, the effect of vulcanizing the rubber component cannot be achieved.On the other hand, when the sulfur content is more than 5 parts by mass,the hardness of the polymer composition increases, and when the polymersheet is used as the inner liner, the durability performance of apneumatic tire may deteriorate. The sulfur content is more preferablymore than or equal to 0.3 parts by mass and less than or equal to 3.0parts by mass.

(Additives in Polymer Composition)

The polymer composition constituting the polymer sheet can containadditives such as stearic acid, zinc oxide, an age inhibitor, and avulcanization accelerator. Stearic acid functions as a vulcanizationassistant for the rubber component. The content of stearic acid ispreferably more than or equal to 1 part by mass and less than or equalto 5 parts by mass relative to 100 parts by mass of the polymercomponent. When the content of stearic acid is less than 1 part by mass,the effect as a vulcanization assistant cannot be achieved. On the otherhand, when the content of stearic acid is more than 5 parts by mass, theviscosity of the polymer composition may be reduced, and breakingstrength may be reduced, which is not preferable. The content of stearicacid is more preferably more than or equal to 1 part by mass and lessthan or equal to 4 parts by mass.

Zinc oxide functions as a vulcanization assistant for the rubbercomponent. The content of zinc oxide is preferably more than or equal to0.1 part by mass and less than or equal to 8 parts by mass relative to100 parts by mass of the polymer component. When the content of zincoxide is less than 0.1 part by mass, the effect as a vulcanizationassistant cannot be achieved. On the other hand, when the content ofzinc oxide is more than 8 parts by mass, the hardness of the polymercomposition increases, and when the polymer sheet is used as the innerliner, the durability performance of a pneumatic tire may deteriorate.The content of zinc oxide is more preferably more than or equal to 0.5parts by mass and less than or equal to 6 parts by mass.

An age inhibitor has a function of preventing a series of degradationscalled aging, such as oxidation degradation, thermal degradation, ozonedegradation, and fatigue degradation. Age inhibitors are classified intoa primary age inhibitor composed of amines or phenols and a secondaryage inhibitor composed of sulfur compounds or phosphites. The primaryage inhibitor has a function of supplying hydrogen to various polymerradicals to stop a chain reaction of autooxidation, and the secondaryage inhibitor exhibits a stabilizing effect by turning hydroxyperoxideinto stable alcohol.

Examples of the age inhibitor include amines, phenols, imidazoles,phosphors, thioureas, and the like. One type of the above-mentioned ageinhibitors may be used solely, or two or more types thereof may be usedin combination. Particularly, it is preferable to useN-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine.

The content of the age inhibitor is preferably more than or equal to 0.1parts by mass and less than or equal to 5 parts by mass relative to 100parts by mass of the polymer component. When the content of the ageinhibitor is less than 0.1 parts by mass, the effect of inhibiting agingcannot be achieved. On the other hand, when the content of the ageinhibitor is more than 5 parts by mass, a blooming phenomenon will occurin the polymer composition. The content of the age inhibitor is morepreferably more than or equal to 0.3 parts by mass and less than orequal to 4 parts by mass.

As a vulcanization accelerator, thiurams, thiazoles, thioureas,dithiocarbamates, guanidines, sulfenamides, and the like can be used.One type of the above-mentioned vulcanization accelerators may be usedsolely, or two or more types thereof may be used in combination.Particularly, it is preferable to use dibenzothiazyl sulfide.

The content of the vulcanization accelerator is preferably more than orequal to 0.1 parts by mass and less than or equal to 5 parts by massrelative to 100 parts by mass of the polymer component. When the contentof the vulcanization accelerator is less than 0.1 parts by mass, theeffect of accelerating vulcanization cannot be achieved. On the otherhand, when the content of the vulcanization accelerator is more than 5parts by mass, the hardness of the polymer composition increases, andwhen the polymer sheet is used as the inner liner, the durabilityperformance of a pneumatic tire may deteriorate. In addition, the rawmaterial cost for the polymer composition increases. The content of thevulcanization accelerator is more preferably more than or equal to 0.3parts by mass and less than or equal to 4 parts by mass.

<Inner Liner Made of Composite Body>

In the present embodiment, as the inner liner, the composite body of thefirst layer made of the polymer sheet and the second layer mainlycomposed of a thermoplastic elastomer is used.

(Second Layer)

In the composite body of the first layer and the second layer, thesecond layer is made of a thermoplastic elastomer composition containinga thermoplastic elastomer and sulfur. In such a second layer, at leastone rubber component selected from the group consisting of naturalrubber, isoprene rubber, and butyl rubber can also be mixed with thethermoplastic elastomer. By adding sulfur to the thermoplasticelastomer, tack strength before vulcanization and vulcanization adhesivestrength with the first layer are improved. Further, tack strengthbefore vulcanization and vulcanization adhesive strength with anadjacent member such as a carcass or an insulation are also improved.

As the thermoplastic elastomer in the second layer, the same one as thatin Embodiment 1-1 can be used.

Particularly, it is preferable to use a styrene-isoprene-styrenetriblock copolymer (SIS), a styrene-isobutylene diblock copolymer (SIB),or an epoxidized styrene-butadiene-styrene triblock copolymer(epoxidized SBS).

Since an isoprene block of the styrene-isoprene-styrene triblockcopolymer (hereinafter also referred to as the SIS) is a soft segment, athermoplastic elastomer composition containing the SIS is easilyvulcanization-bonded with a rubber component. Therefore, when thethermoplastic elastomer composition containing the SIS is used for theinner liner, the inner liner is excellent in adhesiveness with anadjacent rubber constituting a carcass or an insulation, and thus apneumatic tire that can prevent the air-in phenomenon and has excellentdurability can be obtained.

As the SIS and the SIB, the same ones as those in Embodiment 1-1 can beused.

The epoxidized styrene-butadiene-styrene triblock copolymer (hereinafteralso referred to as the epoxidized SBS) is a thermoplastic elastomer inwhich a hard segment is a polystyrene block, a soft segment is abutadiene block, and an unsaturated double bond portion contained in thebutadiene block has been epoxidized. Since the epoxidized SBS has thesoft segment, a thermoplastic elastomer composition containing theepoxidized SBS is easily vulcanization-bonded with a rubber component.Therefore, when the thermoplastic elastomer composition containing theepoxidized SBS is used for the inner liner, the inner liner is excellentin adhesiveness with an adjacent rubber constituting a carcass or aninsulation, and thus a pneumatic tire that can prevent the air-inphenomenon and has excellent durability can be obtained.

Regarding the molecular weight of the epoxidized SBS, the weight-averagemolecular weight obtained by the GPC method is preferably more than orequal to 10,000 and less than or equal to 400,000 in view of rubberelasticity and moldability. When the weight-average molecular weight isless than 10,000, the reinforcing effect may be lessened. When theweight-average molecular weight is more than 400,000, the thermoplasticelastomer composition may have an increased viscosity. Therefore, boththe cases are not preferred.

The content of a styrene unit in the epoxidized SBS is preferably morethan or equal to 10% by mass and less than or equal to 30% by mass inview of tackiness, adhesiveness, and rubber elasticity. In theepoxidized SBS, a molar ratio of a butadiene unit to a styrene unit(butadiene unit/styrene unit) is preferably 90/10 to 70/30. In theepoxidized SBS, the polymerization degree of each block is preferablyabout 500 to 5,000 for a butadiene block and about 500 to 1,500 for astyrene block, in view of rubber elasticity and handling.

When the second layer contains a rubber component, the rubber componentis preferably more than or equal to 20% by mass and less than or equalto 90% by mass, more preferably more than or equal to 30% by mass andless than or equal to 80% by mass, relative to the sum of thethermoplastic elastomer and the rubber component. When the rubbercomponent is less than 20% by mass, the second layer may be unlikely tobe vulcanization-bonded with a carcass layer, and when the rubbercomponent is more than 90% by mass, the second layer and the carcasslayer may be vulcanization-bonded excessively.

The sulfur content is more than or equal to 0.1 parts by mass and lessthan or equal to 5 parts by mass relative to 100 parts by mass of thethermoplastic elastomer. When the sulfur content is less than 0.1 partsby mass, the vulcanization reaction may not be produced. On the otherhand, when the sulfur content is more than 5 parts by mass, thecrosslinking density of the thermoplastic elastomer composition may beincreased, which may increase viscosity. The sulfur content is morepreferably more than or equal to 0.3 parts by mass and less than orequal to 3 parts by mass. The thermoplastic elastomer composition cancontain additives such as stearic acid, zinc oxide, an age inhibitor,and a vulcanization accelerator. For these additives, the formulation inthe first layer can be adopted.

<Method for Manufacturing Inner Liner>

(Polymer Sheet and Composite Body)

The polymer sheet for an inner liner in accordance with the presentinvention can be manufactured by a method described below. Thecompounding agents are charged into a twin-screw extruder and kneadedunder the conditions of about 150 to 280° C. and 50 to 300 rpm, therebyobtaining pellets of a polymer composition in which the SIBS, the rubbercomponent, sulfur, and various additives as necessary are dynamicallycrosslinked. The obtained pellets are charged into a T-die extruder toobtain a sheet-like polymer sheet (or the first layer) made of thepolymer composition and a sheet-like second layer made of athermoplastic elastomer composition.

In the twin-screw extruder, the SIBS, which is a thermoplasticelastomer, serves as the matrix phase, and the rubber component servesas the island phase and is dispersed. Further, in the twin-screwextruder, the rubber component reacts with an additive component, andthe rubber component serving as the island phase produces a crosslinkingreaction. Since the rubber component is dynamically crosslinked in thetwin-screw extruder, so-called dynamic crosslinking is formed. Even ifthe rubber component is dynamically crosslinked in the twin-screwextruder, the shear viscosity of the entire system is low and extrusionmolding is possible because the matrix phase of the system is composedof a thermoplastic elastomer component.

In the pellets of the dynamically-crosslinked polymer compositionobtained with the twin-screw extruder, the rubber component iscrosslinked, whereas the thermoplastic elastomer component of the matrixphase holds plasticity, and serves to produce plasticity of the entirepolymer composition. Therefore, the polymer composition also exhibitsplasticity in T-die extrusion, and thus can be molded into a sheetshape.

Further, since the rubber component is crosslinked in the pellets of thedynamically-crosslinked polymer composition, the polymer composition ofthe inner liner can be prevented from penetrating into the carcass plyeven when a pneumatic tire is heated while manufacturing the pneumatictire by using the polymer sheet fabricated from the pellets as the innerliner.

When the inner liner is composed of a composite body, the first layerand the second layer are bonded with each other. Here, the polymer sheetis used as the first layer. Further, the composite body of the firstlayer and the second layer is formed by lamination extrusion, such aslaminate extrusion or coextrusion, of the respective pellets of thepolymer composition and the thermoplastic elastomer composition.

Embodiment 3-2

Embodiment 3-2 is different from Embodiment 3-1 in that inner liner 2has width W2 formed to be larger than width W1 of unvulcanized rubbersheet 3.

As the cutting step and the joining step, the same methods as those inEmbodiment 1-2 can be used.

<Structure of Tire>

The pneumatic tire manufactured based on Embodiments 3-1, 3-2 can havethe same structure as that in Embodiment 1-1.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be shown in FIG. 9( a). In FIG. 9(a), composite body PL is composed of first layer PL1 and second layerPL2. When composite body PL is used as the inner liner of the pneumatictire, if second layer PL2 is arranged toward the tire radial outer sideso as to contact carcass ply C, adhesive strength between second layerPL2 and carcass C can be enhanced in the tire vulcanization step. Theresultant pneumatic tire has excellent air permeation resistance, sincethe inner liner is satisfactorily bonded with the rubber layer ofcarcass ply C.

<Method for Manufacturing Pneumatic Tire>

As a method for manufacturing the pneumatic tire in accordance with thepresent invention, a conventional manufacturing method can be used. Aninner liner is manufactured using composite body PL. The inner liner isused for a green tire for pneumatic tire 11 and vulcanization-moldedtogether with other members, and thereby the pneumatic tire ismanufactured. When composite body PL is arranged in the green tire,second layer PL2 of composite body PL is arranged toward the tire radialouter side so as to contact carcass ply C. With such an arrangement,adhesive strength between second layer PL2 and carcass 6 can be enhancedin the tire vulcanization step. The resultant pneumatic tire hasexcellent air permeation resistance, since the inner liner issatisfactorily bonded with the rubber layer of carcass ply C.

Embodiment 4-1

As the assembly step, the cutting step, the joining step, and the tiremolding/vulcanization step, the same methods as those in Embodiment 1-1can be used.

It is noted that an inner liner is composed of a composite layer of afirst layer made of a polymer composition containing astyrene-isobutylene-styrene block copolymer and a rubber component andhaving a thickness of 0.05 mm to 0.6 mm, and a second layer disposed ona side of an unvulcanized rubber sheet, made of a thermoplasticelastomer, and having a thickness of 0.01 mm to 0.3 mm. Further, thewidth of the inner liner is adjusted depending on the size of the tire.In the present invention, since the inner liner and the unvulcanizedrubber sheet are pressure-bonded using the rolls, they can be closelybonded reliably with no air left therebetween, and they can be bondedefficiently and with good productivity.

<Inner Liner>

In the present embodiment, the inner liner is composed of a compositebody of the first layer disposed on the inner side of the tire and thesecond layer disposed in contact with a rubber layer of the carcass ply.The first layer is a thermoplastic elastomer composition mainly composedof a styrene-isobutylene-styrene block copolymer (hereinafter alsoreferred to as an “SIBS”), and the second layer is a styrene-basedthermoplastic elastomer composition. At least one of the thermoplasticelastomer compositions of the first and second layers contains 0.1 to100 parts by mass of a tackifier relative to 100 parts by mass of thethermoplastic elastomer.

<First Layer>

The first layer is made of a thermoplastic elastomer composition mainlycomposed of a styrene-isobutylene-styrene block copolymer (SIBS).

As the SIBS, the same one as that in Embodiment 1-1 can be used.

A thickness T1 of the first layer mainly composed of the SIBS is 0.05 to0.6 mm. When the thickness of the first layer is less than 0.05 mm, thefirst layer may be broken by a pressing pressure during vulcanization ofa green tire in which a polymer laminate is used as the inner liner, andthus an air leak phenomenon may occur in the resultant tire. On theother hand, when the thickness of the first layer is more than 0.6 mm,tire weight increases and fuel efficiency performance deteriorates. Thethickness of the first layer is more preferably 0.05 to 0.4 mm. Thefirst layer can be obtained by forming the SIBS into a film by aconventional method of forming a thermoplastic resin or a thermoplasticelastomer into a film, such as extrusion molding or calender molding.

The first layer contains the SIBS by 90% by mass or more in athermoplastic elastomer component. As the thermoplastic elastomer, astyrene-based thermoplastic elastomer, an urethane-based thermoplasticelastomer, or the like can be used.

<Second Layer>

The second layer of the composite body is composed of a styrene-basedthermoplastic elastomer composition.

As the styrene-based thermoplastic elastomer composition, the same oneas that in Embodiment 1-1 can be used.

The thickness of the second layer is preferably 0.01 mm to 0.3 mm. Here,when the second layer is made of, for example, a single layer such as anSIS or SIB layer, the thickness of the second layer refers to athickness of the single layer. On the other hand, when the second layeris made of, for example, two layers including an SIS layer, an SIBlayer, and the like, the thickness of the second layer refers to thetotal thickness of these layers. When the thickness of the second layeris less than 0.01 mm, the second layer may be broken by a pressingpressure during vulcanization of the green tire in which the polymerlaminate is used as the inner liner, and thus vulcanization adhesivestrength may be reduced. On the other hand, when the thickness of thesecond layer is more than 0.3 mm, tire weight may increase and fuelefficiency performance may deteriorate. The thickness of the secondlayer is more preferably 0.05 to 0.2 mm.

<Formulation of Tackifier>

In the present embodiment, at least one of the first layer and thesecond layer is blended with 0.1 to 100 parts by mass of a tackifierrelative to 100 parts by mass of the thermoplastic elastomer. Here, the“tackifier” refers to an additive for increasing tackiness of thethermoplastic elastomer composition. Examples of such a tackifier willbe illustrated below. Further, desirably, the tackifier has aweight-average molecular weight Mw of 1×10² to 1×10⁶ and a softeningpoint within a range of 50° C. to 150° C. When the weight-averagemolecular weight is less than 1×10², a degree of viscosity becomes lowto result in disadvantage in sheet moldability. On the other hand, whenthe weight-average molecular weight is more than 1×10⁶, the first layerand the second layer are provided with insufficient tackiness.

The following is the list of exemplary tackifiers.

[C9 Petroleum Resin]

A C9 petroleum resin is an aromatic petroleum resin obtained bypolymerizing C5 to C9 fractions (mainly C9 fraction) in a mixed state.The C5 to C9 fractions are remnants when obtaining useful compounds,such as ethylene, propylene, and butadiene, by thermally decomposingnaphtha. Examples thereof include products such as: ARKON P70, P90,P100, P125, P140, M90, M100, M115, and M135 (each manufactured byArakawa Chemical Industries, Ltd, and having a softening point of 70 to145° C.); I-MARV S100, S110, P100, P125, and P140 (aromaticcopolymer-based hydrogenated petroleum resins each manufactured byIdemitsu Petrochemical Ltd, having a softening point of 100 to 140° C.,a weight-average molecular weight of 700 to 900, and a bromine number of2.0 to 6.0 g/100 g); and Petcoal XL (manufactured by TOSOH Corporation).

[C5 Petroleum Resin]

A C5 petroleum resin is an aliphatic petroleum resin obtained bypolymerizing C4 to C5 fractions (mainly C5 fraction) in a mixed state.The C4 to C5 fractions are remnants when obtaining useful compounds,such as ethylene, propylene, and butadiene, by thermally decomposingnaphtha. Examples thereof include products such as: Hilets G100(manufactured by Mitsui Petrochemicals Industries, Ltd, and having asoftening point of 100° C.); Marcalets T100AS (manufactured by MaruzenPetrochemical Co., Ltd, and having a softening point of 100° C.); andEscorez 1102 (manufactured by Tonex Co., Ltd, and having a softeningpoint of 110° C.).

[Terpene Resin]

Examples of a terpene resin include products such as: YS Resin PX800N,PX1000, PX1150, PX1250, and PXN1150N; and Clearon P85, P105, P115, P125,P135, P150, M105, M115, and K₁₀₀ (each manufactured by Yasuhara ChemicalCo., Ltd, and having a softening point of 75 to 160° C.).

[Aromatic Modified Terpene Resin]

Examples of an aromatic modified terpene resin include products such as:YS Resin TO85, TO105, TO115, and TO 125 (each manufactured by YasuharaChemical Co., Ltd, and having a softening point of 75 to 165° C.).

[Terpene Phenol Resin]

Examples of a terpene phenol resin include products such as: Tamanol803L and 901 (manufactured by Arakawa Chemical Industries Co., Ltd, andhaving a softening point of 120° C. to 160° C.); and YS Polyster U115,U130, T80, T100, T115, T145, and T160 (each manufactured by YasuharaChemical Co., Ltd, and having a softening point of 75 to 165° C.).

[Cumarone Resin]

Examples of a cumarone resin include a cumarone resin having a softeningpoint of 90° C. (manufactured by Kobe Oil Chemical Industrial Co., Ltd).

[Cumarone Indene Oil]

Examples of a cumarone indene oil include products such as 15E(manufactured by Kobe Oil Chemical Industrial Co., Ltd, and having apour point of 15° C.).

[Rosin Ester]

Examples of a rosin ester include products such as: Ester Gum AAL, A,AAV, 105, AT, H, HP, and HD (each manufactured by Arakawa ChemicalIndustries Co., Ltd, and having a softening point of 68° C. to 110° C.);and Hariester TF, S, C, DS70L, DS90, and DS130 (each manufactured byHarima Chemicals Inc., and having a softening point of 68° C. to 138°C.).

[Hydrogenated Rosin Ester]

Examples of a hydrogenated rosin ester include products such as SuperEster

A75, A100, A115, and A125 (each manufactured by Arakawa ChemicalIndustries Co., Ltd., and having a softening point of 70° C. to 130°C.).

[Alkylphenol Resin]

Examples of an alkylphenol resin include products such as Tamanol 510(manufactured by Arakawa Chemical Industries Co., Ltd, and having asoftening point of 75° C. to 95° C.).

[DCPD]

Examples of a DCPD include products such as Escorez 5300 (manufacturedby Tonex Co., Ltd, and having a softening point of 105° C.).

As the tackifier, a fully hydrogenated petroleum resin of the C9petroleum resins is well compatible with the SIB, and can improveadhesiveness without deteriorating gas barrier property. Further, it hasan effect of decreasing a degree of viscosity, and can be usedadvantageously for film extrusion molding.

The tackifier is blended in a range of 0.1 to 100 parts by mass,preferably 1 to 50 parts by mass, relative to 100 parts by mass of thethermoplastic elastomer of the first layer. When the tackifier is lessthan 0.1 parts by mass, vulcanization adhesive strength with the secondlayer is insufficient. On the other hand, when the tackifier is morethan 100 parts by mass, tackiness becomes too high, with the result thatworkability and productivity are decreased and gas barrier property isalso deteriorated.

The second layer is disposed between the first layer on the inner sideof the tire and the carcass ply, and is required to have adhesivenesswith both of them. To attain this, the tackifier is blended in a rangeof 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass, relativeto 100 parts by mass of the thermoplastic elastomer of the second layer.When the tackifier is less than 0.1 parts by mass, vulcanizationadhesive strength with the first layer is insufficient. On the otherhand, when the tackifier is more than 100 parts by mass, tackinessbecomes too high, with the result that workability and productivity aredecreased and gas barrier property is also deteriorated.

<Second layer: SIBS Mixture>

In the present embodiment, the second layer can be composed of a mixtureof a styrene-based thermoplastic elastomer and the SIBS, particularly amixture layer of the SIS and the SIBS or a mixture of the SIB and theSIBS. In this case, the blending quantity of the SIBS is adjusted in arange of 10 to 80% by mass, preferably 30 to 70% by mass, of athermoplastic elastomer component. When the SIBS is less than 10% bymass, adhesiveness with the first layer is likely to be reduced, andwhen the SIBS is more than 80% by mass, adhesiveness with the carcassply is likely to be reduced.

<Composite Body>

In the present embodiment, the composite body formed of the first layerand the second layer is used as the inner layer. Here, the first layerand the second layer are thermoplastic elastomer compositions, and arein a softened state in a mold at a vulcanization temperature, forexample 150° C. to 180° C. The softened state refers to an intermediatestate between a solid and a liquid with improved molecular mobility.Further, a thermoplastic elastomer composition in the softened state islikely to adhere to or to be bonded with an adjacent member.Accordingly, in order to manufacture a tire, a cooling step is requiredto prevent a change in the shape of a thermoplastic elastomer and itsadhesion or fusion to the adjacent member. In the cooling step, theinside of a bladder is cooled rapidly to 50 to 120° C. for 10 to 300seconds after vulcanization of the tire. As a cooling medium, at leastone selected from air, steam, water, and oil is used. By adopting such acooling step, a thin inner liner in the range of 0.05 to 0.6 mm can beformed as the inner liner.

<Method for Manufacturing Pneumatic Tire>

The pneumatic tire in accordance with the present embodiment can bemanufactured by molding a green tire using the inner liner obtained bythe aforementioned method and an unvulcanized rubber sheet (carcass ply)together with other members, and thereafter vulcanizing them. Whencomposite body PL is arranged in the green tire, second layer PL2 isarranged toward the tire radial outer side so as to contact carcass plyC. With such an arrangement, the second layer made of a styrene-basedthermoplastic elastomer composition, for example, the SIS layer or theSIB layer, can have an improved adhesive strength with carcass ply C inthe tire vulcanization step. The resultant pneumatic tire has excellentair permeation resistance and durability, since the inner liner issatisfactorily bonded with the rubber layer of carcass ply C.

Embodiment 4-2

Embodiment 4-2 is different from Embodiment 4-1 in that inner liner 2has width W2 formed to be larger than width W1 of unvulcanized rubbersheet 3.

As the cutting step and the joining step, the same methods as those inEmbodiment 1-2 can be used.

<Inner Liner>

In Embodiment 4-2, for an inner liner, the same thermoplastic elastomercompositions as those in Embodiment 4-1 are used, and the samethicknesses thereof are also adopted.

<Method for Manufacturing Pneumatic Tire>

In a method for manufacturing the pneumatic tire in Embodiments 4-1,4-2, firstly, the inner liner and an unvulcanized rubber sheet (carcassply) are laminated using composite body PL to manufacture a laminate.Using the laminate, a green tire is molded together with other members,and thereafter vulcanized to manufacture a pneumatic tire. Whencomposite body PL is arranged in the green tire, second layer PL2 ofcomposite body PL is arranged toward the tire radial outer side so as tocontact carcass ply C. With such an arrangement, adhesive strengthbetween second layer PL2 and carcass 6 can be enhanced in the tirevulcanization step. The resultant pneumatic tire has excellent airpermeation resistance, since the inner liner is satisfactorily bondedwith the rubber layer of carcass ply C.

<Structure of Tire>

The pneumatic tire manufactured based on Embodiments 4-1, 4-2 can havethe same structure as that in Embodiment 1-1.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be shown in FIG. 9( a). In FIG. 9(a), composite body PL is composed of first layer PL1 and second layerPL2. When composite body PL is used as the inner liner of the pneumatictire, if second layer PL2 is arranged toward the tire radial outer sideso as to contact carcass ply C, adhesive strength between second layerPL2 and carcass C can be enhanced in the tire vulcanization step. Theresultant pneumatic tire has excellent air permeation resistance, sincethe inner liner is satisfactorily bonded with the rubber layer ofcarcass ply C.

Embodiment 5-1

As the assembly step, the cutting step, the joining step, and the tiremolding/vulcanization step, the same methods as those in Embodiment 1-1can be used.

It is noted that an inner liner is a single layer of a polymer sheetmade of an elastomer composition mainly composed of an isobutylene-basedmodified copolymer, and having a thickness of 0.05 mm to 0.6 mm, oralternatively, an inner liner is composed of a composite layer of afirst layer made of the polymer sheet and a second layer disposed on aside of an unvulcanized rubber sheet, made of a thermoplastic elastomer,and having a thickness of 0.01 mm to 0.3 mm. Further, the width of theinner liner is adjusted depending on the size of the tire.

Embodiment 5-2

Embodiment 5-2 is different from Embodiment 5-1 in that inner liner 2has width W2 formed to be larger than width W1 of unvulcanized rubbersheet 3.

As the cutting step and the joining step, the same methods as those inEmbodiment 1-2 can be used.

<Inner Liner>

The inner liner used in Embodiments 5-1, 5-2 is composed of a compositelayer of the first layer disposed on the inner side of the tire and thesecond layer disposed in contact with a rubber layer of the carcass ply.In addition, either the first layer or the second layer is composed ofan elastomer composition containing an isobutylene-based modifiedcopolymer.

<Isobutylene-Based Modified Copolymer>

In the present embodiment, the isobutylene-based modified copolymer isan isobutylene-based modified copolymer made of a polymer block (A)mainly composed of isobutylene and a polymer block (B) mainly composedof an aromatic vinyl-based compound, and is a random copolymer in whichat least one of the blocks contains 3-pinene.

Here, the isobutylene-based modified copolymer is typically a copolymerin which β-pinene is contained in a styrene block of astyrene-isobutylene-styrene block copolymer (SIBS), astyrene-isoprene-styrene block copolymer (SIS), or a styrene-isobutyleneblock copolymer (SIB).

The polymer block (A) mainly composed of isobutylene is a polymer blockin which a unit whose soft segment is derived from isobutylene occupiesmore than or equal to 80% by mass. Such a polymer block can bemanufactured using aliphatic olefins, dienes, vinyl ethers, silanes,vinylcarbazole, acenaphthylene, or the like as a monomer component.

On the other hand, the polymer block (B) mainly composed of an aromaticvinyl-based compound is a polymer block in which a unit whose hardsegment is derived from the aromatic vinyl-based compound occupies morethan or equal to 80% by mass.

Examples of the aromatic vinyl-based compound include styrene,methylstyrene, α-methylstyrene, β-methylstyrene, 2,6-dimethylstyrene,2,4-dimethylstyrene, α-methyl-o-methylstyrene, α-methyl-m-methylstyrene,α-methyl-p-methylstyrene, β-methyl-o-methylstyrene,β-methyl-m-methylstyrene, β-methyl-p-methylstyrene,2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene,α-methyl-2,4-dimethylstyrene, 3-methyl-2,6-dimethylstyrene,β-methyl-2,4-dimethylstyrene, chlorostyrene, 2,6-dichlorostyrene,2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α-chloro-m-chlorostyrene,α-chloro-p-chlorostyrene, β-chloro-o-chlorostyrene,β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene,2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene,α-chloro-2,4-dichlorostyrene, β-chloro-2,6-dichlorostyrene,β-chloro-2,4-dichlorostyrene, t-butylstyrene, methoxy styrene,chloromethylstyrene, bromomethylstyrene, and the like. In view of cost,styrene and α-methylstyrene are particularly preferable.

In the isobutylene-based modified copolymer of the present embodiment,at least one of the polymer blocks (A) and (B) is a random copolymerwith β-pinene. In view of low-temperature characteristics, it ispreferable that β-pinene has been copolymerized with the polymer block(B) mainly composed of an aromatic vinyl-based compound.

On the other hand, in view of adhesiveness, it is preferable thatβ-pinene has been copolymerized with the polymer block (A) mainlycomposed of isobutylene. In this case, the content of β-pinene ispreferably 0.5 to 25% by mass, and more preferably 2 to 25% by mass, ofthe isobutylene-based modified copolymer. When the content of β-pineneis less than 0.5% by mass, adhesiveness is insufficient. When thecontent of β-pinene us more than 25% by mass, it will become fragile,and rubber elasticity is likely to be decreased.

In the present embodiment, there is no particular limitation on thestructure of the isobutylene-based modified copolymer, and any of ablock copolymer, a triblock copolymer, a multi-block copolymer, and thelike having a linear, branched, or star molecular chain structure can beselected. In view of property balance and molding workability, astructure in which the polymer blocks (A) and (B) constitute a diblockcopolymer ((A)-(B)) or a triblock copolymer ((B)-(A)-(B)) can beadopted. They can be used solely, or two or more types thereof can beused in combination, in order to obtain desired physical properties andmolding workability.

Further, as for the molecular weight of the isobutylene-based modifiedcopolymer, the weight-average molecular weight obtained by GPCmeasurement is preferably 30,000 to 300,000, and particularly preferably30,000 to 150,000, in view of fluidity, molding workability, rubberelasticity, and the like. When the weight-average molecular weight isless than 30,000, mechanical physical properties are less likely to befully exhibited. On the other hand, when the weight-average molecularweight is more than 300,000, fluidity and workability are likely todeteriorate. Furthermore, in view of processing stability, the value ofmolecular weight distribution of the isobutylene-based modifiedcopolymer (weight-average molecular weight/number-average molecularweight) is preferably less than or equal to 1.3.

<Method for Manufacturing Isobutylene-Based Modified Copolymer>

A method for manufacturing an isobutylene-based modified copolymer isdisclosed, for example, in Japanese Patent Laying-Open No. 2010-195969.For example, the isobutylene-based modified copolymer can bemanufactured by polymerizing the above-described monomer componentsunder the presence of a polymerization initiator expressed by a generalformula (I) indicated below.

(CR¹R²X)_(n)R³  (1)

(where X is a substituent selected from a halogen atom, an alkoxy grouphaving 1 to 6 carbon atoms, and an acyloxy group, each of R¹ and R² is ahydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbonatoms, R¹ and R² may be the same or may be different, R³ is a monovalentor multivalent aromatic hydrocarbon group, or a monovalent ormultivalent aliphatic hydrocarbon group, and n indicates a naturalnumber of 1 to 6).

The compound expressed by the above general formula (I) will be aninitiator, and generates carbocations under the presence of Lewis acidor the like to be a starting point of cationic polymerization. Examplesof the compound expressed by the above general formula (I) includebis(1-chloro-1-methylethyl)benzene [C₆H₄(C(CH₃)₂Cl)₂] andtris(1-chloro-1-methylethyl)benzene [(ClC(CH₃)₂)₃C₆H₃].

When manufacturing an isobutylene-based modified copolymer, a Lewis acidcatalyst can further be present together. Lewis acid can be used forcationic polymerization, and a metal halide such as TiCl₄, TiBr₄, BCl₃,BF₃, BF₃.OEt₂, ZnBr₂, or AlCl₃, or an organic metal halide such asEt₂AlCl or EtAlCl₂ can be used, for example. The above Lewis acid can beused by 0.1 to 100 molar equivalent relative to the compound expressedby the general formula (1).

Further, when manufacturing the isobutylene-based modified copolymer, anelectron donor component can also be present together. Examples of thiselectron donor component include pyridines, amines, amides, andsulfoxides.

Polymerization of the isobutylene-based modified copolymer can beperformed in an organic solvent. Here, an organic solvent that does notinhibit cationic polymerization can be used. For example, a halogenatedhydrocarbon such as methyl chloride, dichloromethane, chloroform, ethylchloride, and dichloroethane, alkylbenzenes such as benzene, toluene,xylene, and ethylbenzene, linear aliphatic hydrocarbons such as ethane,propane, butane, pentane, hexane, and heptane, branched aliphatichydrocarbons such as 2-methylpropane and 2-methylbutane, or cyclicaliphatic hydrocarbons such as cyclohexane, methylcyclohexane, andethylcyclohexane can be used.

In view of viscosity adjustment and heat dissipation of a copolymersolution to be generated, the amount of the above-mentioned organicsolvent is adjusted such that the copolymer has a concentration of 5 to40% by mass. It is noted that a copolymerization reaction in the rangeof −20° C. to −70° C. is preferable.

<Elastomer Composition of First Layer>

In the present embodiment, an elastomer component of the elastomercomposition used for the first layer of the inner layer is composed ofan isobutylene-based modified copolymer alone, or a mixture of anisobutylene-based modified copolymer and another elastomer component.

The isobutylene-based modified copolymer ranges from 10 to 100% by mass,preferably 30 to 100% by mass, of the entire elastomer component. Whenthe isobutylene-based modified copolymer is less than 10% by mass,vulcanization adhesive strength with the second layer may be reduced.

As the elastomer component, a thermoplastic elastomer, in particular astyrene-based thermoplastic elastomer is suitably used. Here, thestyrene-based thermoplastic elastomer refers to a copolymer containing astyrene block as a hard segment. Examples thereof include astyrene-isoprene-styrene block copolymer (SIS), a styrene-isobutyleneblock copolymer (SIB), a styrene-butadiene-styrene block copolymer(SBS), a styrene-isobutylene-styrene block copolymer (SIBS), astyrene-ethylene-butene-styrene block copolymer (SEBS), astyrene-ethylene-propylene-styrene block copolymer (SEPS), astyrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), anda styrene-butadiene-butylene-styrene block copolymer (SBBS).

Further, the styrene-based thermoplastic elastomer may have an epoxygroup in its molecular structure, and for example an epoxy-modifiedstyrene-butadiene-styrene copolymer (epoxidized SBS) such as EpofriendA1020 manufactured by Daicel Chemical Industries, Ltd. (having aweight-average molecular weight of 100,000 and an epoxy equivalent of500) can be used. It is noted that, among styrene-based thermoplasticelastomers, a styrene-isobutylene-styrene block copolymer is suitablyused.

A rubber component can be mixed as the elastomer component of the firstlayer. By mixing the rubber component, tackiness with the adjacentcarcass ply in an unvulcanized state is imparted, and vulcanizationadhesiveness with the carcass ply or the insulation can be increasedthrough vulcanization.

The rubber component preferably contains at least one selected from thegroup consisting of natural rubber, isoprene rubber, chloroprene rubber,and butyl rubber. The blending quantity of the rubber componentpreferably ranges from 5 to 20% by mass of a thermoplastic polymercomponent.

The thickness of the first layer is 0.05 to 0.6 mm. When the thicknessof the first layer is less than 0.05 mm, the first layer may be brokenby a pressing pressure during vulcanization of a green tire in which apolymer laminate is used as the inner liner, and thus an air leakphenomenon may occur in the resultant tire. On the other hand, when thethickness of the first layer is more than 0.6 mm, tire weight increasesand fuel efficiency performance deteriorates. The thickness of the firstlayer is more preferably 0.05 to 0.4 mm. The first layer can be obtainedby forming the SIBS into a film by a conventional method of forming athermoplastic resin or a thermoplastic elastomer into a film, such asextrusion molding or calender molding.

<Elastomer Composition of Second Layer>

In the present embodiment, an elastomer component of the elastomercomposition used for the second layer of the inner layer is composed ofa mixture of an isobutylene-based modified copolymer and anotherelastomer component.

The isobutylene-based modified copolymer ranges from 5 to 80% by mass,preferably 10 to 60% by mass, of the entire elastomer component. Whenthe isobutylene-based modified copolymer is less than 5% by mass,vulcanization adhesive strength with the first layer may be reduced.When the isobutylene-based modified copolymer is more than 80% by mass,vulcanization adhesion with the carcass ply may be reduced.

As the elastomer component of the elastomer composition used for thesecond layer, a thermoplastic elastomer, in particular a styrene-basedthermoplastic elastomer is suitably used. As the styrene-basedthermoplastic elastomer, the same one as that in Embodiment 1-1 can beused.

The thickness of the second layer is preferably 0.01 mm to 0.3 mm. Here,when the second layer is made of, for example, a single layer such as anSIS or SIB layer, the thickness of the second layer refers to athickness of the single layer. On the other hand, when the second layeris made of, for example, two or three layers including an SIS layer, anSIB layer, and the like, the thickness of the second layer refers to thetotal thickness of these layers. When the thickness of the second layeris less than 0.01 mm, the second layer may be broken by a pressingpressure during vulcanization of the green tire in which the polymerlaminate is used as the inner liner, and thus vulcanization adhesivestrength may be reduced. On the other hand, when the thickness of thesecond layer is more than 0.3 mm, tire weight may increase and fuelefficiency performance may deteriorate. The thickness of the secondlayer is more preferably 0.05 to 0.2 mm.

Further, the styrene-based thermoplastic elastomer may have an epoxygroup in its molecular structure, and for example an epoxy-modifiedstyrene-butadiene-styrene copolymer (epoxidized SBS) such as EpofriendA1020 manufactured by Daicel Chemical Industries, Ltd. (having aweight-average molecular weight of 100,000 and an epoxy equivalent of500) can be used.

<SIBS Mixture>

At least one of the first layer and the second layer can be composed ofa mixture of the SIS and the SIBS, or a mixture of the SIB and the SIBS.In this case, the mixing quantity of the SIBS is adjusted in a range of10 to 80% by mass, preferably 30 to 70% by mass, of the elastomercomponent. When the SIBS is less than 10% by mass, adhesiveness with thefirst layer is likely to be reduced, and when the SIBS is more than 80%by mass, adhesiveness with the carcass ply is likely to be reduced.

<Tackifier>

In the present embodiment, at least one of the first layer and thesecond layer is blended with 0.1 to 100 parts by mass of a tackifierrelative to 100 parts by mass of the elastomer component. Here, thetackifier refers to a compounding agent for increasing tackiness of theelastomer composition. For example, the same tackifier as that inEmbodiment 4-1 can be used.

<Additives in Elastomer Composition>

The elastomer compositions of the first and second layers can be addedwith a crosslinking agent and a crosslinking assistant. As thecrosslinking agent, sulfur, tetramethylthiuram disulfide,4,4-dithiobismorpholine, organic peroxide, phenol-formaldehyde resin, orhalomethylphenol can be used.

As the crosslinking assistant, a metal oxide such as sulfenamide,benzothiazyl, guanidine, dithiocarbamic acid, and zinc oxide; analiphatic acid such as stearic acid; a nitrogen-containing compound,triallyl isocyanurate, ethylene glycol dimethacrylate, ortrimethylolpropane methacrylate can be used. The blending quantity ofthe crosslinking agent and the crosslinking assistant is 0.3 to 6 partsby mass relative to 100 parts by mass of the elastomer component.

The elastomer compositions can be further added with a filler, an ageinhibitor, a softener, a processing assistant, and the like. As thefiller, carbon black, wet silica, dry silica, calcium carbonate, kaolin,talc, clay, or the like can be used. The age inhibitor includes anantioxidant, an ultraviolet absorber, and a light stabilizer. As thesoftener, a paraffinic oil, a napthenic oil, an aromatic oil, rapeseedoil, di-octylphthalate, or the like can be used. Further, as theprocessing assistant, a higher fatty acid, a fatty acid ester, a fattyacid metal salt, a fatty acid amide, paraffin wax, a fatty alcohol, afluorine/silicone-based resin, or the like can be used.

<Structure of Tire>

The pneumatic tire manufactured based on Embodiments 5-1, 5-2 can havethe same structure as that in Embodiment 1-1.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be shown in FIG. 9( a). In FIG. 9(a), composite layer PL is composed of first layer PL1 and second layerPL2. When composite layer PL is used as the inner liner of the pneumatictire, if second layer PL2 is arranged toward the tire radial outer sideso as to contact carcass ply C, adhesive strength between second layerPL2 and carcass C can be enhanced in the tire vulcanization step. Theresultant pneumatic tire has excellent air permeation resistance, sincethe inner liner is satisfactorily bonded with the rubber layer ofcarcass ply C.

<Method for Manufacturing Pneumatic Tire>

As a method for manufacturing the pneumatic tire in accordance with thepresent invention, a conventional manufacturing method can be used. Aninner liner is manufactured using composite layer PL. The inner liner isused for a green tire for pneumatic tire 11 and vulcanization-moldedtogether with other members, and thereby the pneumatic tire ismanufactured. When composite layer PL is arranged in the green tire,second layer PL2 of composite layer PL is arranged toward the tireradial outer side so as to contact carcass ply C. With such anarrangement, adhesive strength between second layer PL2 and carcass 6can be enhanced in the tire vulcanization step. The resultant pneumatictire has excellent air permeation resistance, since the inner liner issatisfactorily bonded with the rubber layer of carcass ply C.

Embodiment 6-1

As the assembly step, the cutting step, the joining step, and the tiremolding/vulcanization step, the same methods as those in Embodiment 1-1can be used.

It is noted that an inner liner is composed of a composite layer of afirst layer made of an elastomer composition containing an SIBS modifiedcopolymer and having a thickness of 0.05 mm to 0.6 mm, and a secondlayer disposed on a side of an unvulcanized rubber sheet, made of athermoplastic elastomer, and having a thickness of 0.01 mm to 0.3 mm.Further, the width of the inner liner is adjusted depending on the sizeof the tire.

Embodiment 6-2

Embodiment 6-2 is different from Embodiment 6-1 in that inner liner 2has width W2 formed to be larger than width W1 of unvulcanized rubbersheet 3.

As the cutting step and the joining step, the same methods as those inEmbodiment 1-2 can be used.

<Inner Liner>

The inner liner used in Embodiments 6-1, 6-2 is composed of a compositelayer of the first layer disposed on the inner side of the tire and thesecond layer disposed in contact with a rubber layer of the carcass ply.

The first layer is a thermoplastic elastomer composition containing anSIBS modified copolymer having a styrene block moiety of astyrene-isobutylene-styrene block copolymer (hereinafter also referredto as an “SIBS”) modified with an acid chloride or an acid anhydridehaving an unsaturated bond.

Further, the second layer is an elastomer composition containing atleast one of a styrene-isoprene-styrene block copolymer (hereinafteralso referred to as an “SIS”) and a styrene-isobutylene block copolymer(hereinafter also referred to as an “SIB”).

<First Layer>

The first layer is a composition containing an SIBS modified copolymerby 10% by mass to 100% by mass of an elastomer component. The SIBSmodified copolymer is obtained by modifying a styrene block moietythereof with an acid chloride or an acid anhydride having an unsaturatedbond, and contains a chemical structure expressed by formula (VI) belowin a molecular chain.

In formula (VI), R¹ is a monovalent organic group having a functionalgroup. Examples of the acid chloride having an unsaturated bond used formodification in the present invention include methacrylic acid chloride,methacrylic acid bromide, methacrylic acid iodide, acrylic acidchloride, acrylic acid bromide, acrylic acid iodide, crotonic acidchloride, and crotonic acid bromide. In particular, methacrylic acidchloride and acrylic acid chloride are suitable.

Examples of the acid anhydride include acetic anhydride, maleicanhydride, phthalic anhydride, and the like. Acetic anhydride isparticularly suitable. Two or more types of these compounds can also beused in combination. Through such modification, an unsaturated group isintroduced into the SIBS, which enables crosslinking through the use ofa crosslinking agent.

As described above, the blending quantity of the SIBS modified copolymerranges from 10 to 100% by mass, preferably 30 to 100% by mass, of theelastomer component. When the blending quantity of the SIBS modifiedcopolymer is less than 10% by mass of the elastomer component,vulcanization adhesion between the first layer and both of the secondlayer and a carcass ply rubber may be insufficient.

The SIBS modified copolymer contains an acid chloride and an acidanhydride having an unsaturated bond at a content of more than or equalto 1% by weight, preferably more than or equal to 5% by weight, and lessthan or equal to 30% by weight. In order to crosslink the SIBS modifiedcopolymer, a conventional method can be used. For example, thermalcrosslinking by heating and crosslinking with a crosslinking agent canbe performed. As the crosslinking agent, an organic peroxide, such as,for example, dicumylperoxide, di-tert-butyl peroxide, or2,5-dimethyl-2,5-di-(tert-butylperoxy) hexane can be used. The blendingquantity of the organic peroxide preferably ranges from 0.1 to 3.0 partsby mass relative to 100 parts by mass of an thermoplastic elastomercomponent.

In the present embodiment, for the elastomer composition of the firstlayer, a polyfunctional vinyl monomer (e.g., divinylbenzene, triarylcyanurate), or a polyfunctional methacrylate monomer (e.g., ethyleneglycol dimethacrylate, diethylene glycol dimethacrylate, triethyleneglycol dimethacrylate, polyethylene glycol dimethacrylate,trimethylolpropane trimetacrylate, allyl methacrylate) can be used incombination as a crosslinking agent. In this case, the composition aftercrosslinking can be expected to have improved flex crackcharacteristics.

Since the SIBS modified copolymer is derived from an isobutylene block,a film made of the SIBS modified copolymer has excellent air permeationresistance. Further, since the unsaturated group is introduced into theSIBS in the SIBS modified copolymer, thermal crosslinking andcrosslinking with a crosslinking agent can be performed. Thus, flexcrack characteristics and air permeation resistance are improvedtogether with basic characteristics such as tensile strength, elongationat break, and permanent strain, and accordingly, characteristics as theinner liner are improved.

When a pneumatic tire is manufactured by using a polymer film made ofthe elastomer composition containing the SIBS modified copolymer for theinner liner, air permeation resistance can be ensured. Therefore, it isnot necessary to use a halogenated rubber having a high specific gravitysuch as halogenated butyl rubber, which has been conventionally used toimpart air permeation resistance, and even if the halogenated rubber isused, the amount of use can be reduced. This enables weight saving ofthe tire and improves fuel efficiency.

Although there is no particular limitation on the molecular weight ofthe SIBS modified copolymer, the weight-average molecular weightobtained by GPC measurement is preferably 50,000 to 400,000 in view offluidity, workability, rubber elasticity, and the like. When theweight-average molecular weight is less than 50,000, tensile strengthand tensile elongation may decrease. When the weight-average molecularweight is more than 400,000, extrusion moldability may deteriorate.Therefore, both the cases are not preferred. In the SIBS modifiedcopolymer, in view of further improving air permeation resistance anddurability, the content of a styrene component in the SIBS is 10 to 30%by mass, preferably 14 to 23% by mass.

In the SIBS as a copolymer, the polymerization degree of each block ispreferably about 10,000 to 150,000 for isobutylene and about 5,000 to30,000 for styrene, in view of rubber elasticity and handling (when thepolymerization degree is less than 10,000, the SIBS becomes a liquid).

<Manufacturing of SIBS Modified Copolymer>

The SIBS can be obtained by a conventional living cationicpolymerization method for a vinyl-based compound. For example, JapanesePatent Laying-Open No. 62-048704 and Japanese Patent Laying-Open No.64-062308 disclose that living cationic polymerization of isobutylenewith other vinyl compounds can be performed, and a polyisobutylene-basedblock copolymer can be manufactured by using isobutylene and othercompounds as the vinyl compounds.

For manufacturing the SIBS modified copolymer, the following method canbe adopted for example. The styrene-isobutylene-styrene block copolymeris charged into a separable flask, and then the inside of apolymerization vessel is substituted by nitrogen. Then, an organicsolvent (e.g., n-hexane and butyl chloride) having been dried withmolecular sieves is added, and methacrylic acid chloride is furtheradded. At last, aluminum trichloride is added while stirring thesolution to produce a reaction. A predetermined amount of water is addedto the reaction solution after a certain period of time since the startof reaction, and the solution is stirred. The reaction is thenterminated. The reaction solution is washed several times or more with alarge amount of water, and further, slowly dropped into a large amountof a methanol-acetone mixed solvent to precipitate a polymer. Theresulting polymer is vacuum dried to obtain the SIBS modified copolymer.It is noted that a method for manufacturing an SIBS modified copolymeris disclosed for example in Japanese Patent No. 4551005.

<Elastomer Composition Containing SIBS Modified Copolymer>

The first layer is an elastomer composition containing the SIBS modifiedcopolymer. That is, the first layer preferably contains the SIBSmodified copolymer by more than or equal to 10% by mass, more preferablymore than or equal to 35% by mass, in the elastomer component. As theelastomer component, a styrene-based thermoplastic elastomer, anurethane-based thermoplastic elastomer, or the like can be suitablyused.

The thickness of the first layer is 0.05 to 0.6 mm. When the thicknessof the first layer is less than 0.05 mm, the first layer may be brokenby a pressing pressure during vulcanization of a green tire in which apolymer laminate composed of the first and second layers is used as theinner liner, and thus an air leak phenomenon may occur in the resultanttire. On the other hand, when the thickness of the first layer is morethan 0.6 mm, tire weight increases and fuel efficiency performancedeteriorates. The thickness of the first layer is more preferably 0.05to 0.4 mm. The first layer can be obtained by adopting a conventionalmethod of forming a thermoplastic resin or a thermoplastic elastomerinto a film, such as extrusion molding or calender molding.

<Second Layer>

The second layer is a composition containing either one thermoplasticelastomer of a styrene-isoprene-styrene block copolymer (SIS) and astyrene-isobutylene block copolymer (SIB). Further, the second layer cancontain an SIBS modified copolymer, a styrene-based thermoplasticelastomer, or a rubber component. The SIBS modified copolymer preferablyranges from 5 to 80% by mass, more preferably 10 to 80% by mass, of theentire thermoplastic elastomer component. When the SIBS modifiedcopolymer is less than 5% by mass, vulcanization adhesive strength withthe first layer may be reduced, and when the SIBS modified copolymer ismore than 80% by mass, adhesive strength with the carcass ply may bereduced.

Here, the styrene-based thermoplastic elastomer refers to a copolymercontaining a styrene block as a hard segment. For example, the same oneas that in Embodiment 1-1 can be used.

<Mixture with SIBS>

In the present invention, the second layer can be composed of a mixtureof the SIS and the SIBS, or a mixture of the SIB and the SIBS. In thiscase, the blending quantity of the SIBS is adjusted in a range of 10 to80% by mass of the elastomer component. When the SIBS is less than 10%by mass, adhesiveness with the first layer is likely to be reduced, andwhen the SIBS is more than 80% by mass, adhesiveness with the carcassply is likely to be reduced.

<Tackifier>

In the present embodiment, at least one of the first layer and thesecond layer can be blended with a tackifier in a range of 0.1 to 100parts by mass relative to 100 parts by mass of the elastomer component.Here, the tackifier refers to a compounding agent for increasingtackiness of the elastomer composition, and for example, the same one asthat in Embodiment 4-1 can be used.

The tackifier is blended in a range of 0.1 to 100 parts by mass,preferably 1 to 50 parts by mass, relative to 100 parts by mass of theelastomer component of the first layer. When the tackifier is less than0.1 parts by mass, vulcanization adhesive strength with the second layeris insufficient. On the other hand, when the tackifier is more than 100parts by mass, tackiness becomes too high, with the result thatworkability and productivity are decreased and gas barrier property isalso deteriorated.

The second layer is disposed between the first layer on the inner sideof the tire and the carcass ply, and is required to have adhesivenesswith both of them. To attain this, the tackifier is blended in a rangeof 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass, relativeto 100 parts by mass of the elastomer component of the second layer.When the tackifier is less than 0.1 parts by mass, vulcanizationadhesive strength with the first layer is insufficient. On the otherhand, when the tackifier is more than 100 parts by mass, tackinessbecomes too high, with the result that workability and productivity aredecreased and gas barrier property is also deteriorated.

<Rubber Component>

The elastomer composition of the first layer or the second layer can beblended with a rubber component. By blending the rubber component,tackiness with the adjacent carcass ply in an unvulcanized state isimparted, and vulcanization adhesiveness with the carcass ply or theinsulation can be increased through vulcanization.

The rubber component preferably contains at least one selected from thegroup consisting of natural rubber, isoprene rubber, chloroprene rubber,and butyl rubber. The blending quantity of the rubber componentpreferably ranges from 5 to 75% by mass in a polymer component.

<Ultraviolet Absorber and Antioxidant>

In the present embodiment, the elastomer composition preferably containsan ultraviolet absorber. The ultraviolet absorber absorbs light in anultraviolet range having a wavelength of more than or equal to 290 nm toprevent deterioration of the molecular chain of a polymer compound. Forexample, benzophenone-based, salicylate-based, and benzotriazol-basedultraviolet absorbers absorb ultraviolet light having a wavelength ofaround 320 nm to 350 nm where the polymer compound is most likely tosuffer from deterioration. The absorbers have a function of convertinglight in this wavelength range into vibrational energy or thermalenergy, thereby preventing absorption into the polymer compound. Inparticular, the benzotriazol-based ultraviolet absorber can absorb awide range of ultraviolet light. Here, examples of the ultravioletabsorber are listed below.

[Benzotriazol-Based Ultraviolet Absorber]

Examples of the benzotriazol-based ultraviolet absorber can include:TINUVIN P/FL (manufactured by BASF, and having a molecular weight of225, a melting point of 128 to 132° C., and a maximum absorptionwavelength of 341 nm) (2-(2-hydroxy-benzotriazol-2-yl)-p-cresol);TINUVIN 234 (manufactured by BASF, and having a molecular weight of447.6, a melting point of 137 to 141° C., and a maximum absorptionwavelength of 343 nm) (2-[2-hydroxy-3,5-bis(α,α′dimethylbenzyl)phenyl]-2H-benzotriazol); TINUVIN 326/FL (manufactured byBASF, and having a molecular weight of 315.8, a melting point of 138 to141° C., and a maximum absorption wavelength of 353 nm); ADK STAB LA-36(manufactured by ADEKA Corporation)(2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazol);TINUVIN 237 (manufactured by BASF, and having a molecular weight of338.4, a melting point of 139 to 144° C., and a maximum absorptionwavelength of 359 nm)(2,4-di-t-butyl-6-(5-chlorobenzotriazol-2-yl-)phenol); TINUVIN 328(manufactured by BASF, and having a molecular weight of 351.5, a meltingpoint of 80 to 88° C., and a maximum absorption wavelength of 347 nm)(2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazol); and TINUVIN 329/FL(manufactured by BASF, and having a molecular weight of 323, a meltingpoint of 103 to 105° C., and a maximum absorption wavelength of 343 nm)(2-(2-hydroxy-benzotriazol-2-yl)-4-tert-octylphenol).

[Liquid Ultraviolet Absorber]

Examples of a liquid ultraviolet absorber can include: TINUVIN 213(manufactured by BASF, and having a melting point of −40° C. and amaximum absorption wavelength of 344 nm)(5-(2-hydroxy-benzotriazol-2-yl)-4-hydroxy-3-tert-butylbenzenpropanoicacid methyl); TINUVIN 571 (manufactured by BASF, and having a molecularweight of 393.6, a melting point of −56° C., and a maximum absorptionwavelength of 343 nm)(2-(2-hydroxybenzotriazol-2-yl)-4-methyl-6-dodecylphenol); TINUVIN1577FF (manufactured by BASF, and having a molecular weight of 425, amelting point of 148° C., and a maximum absorption wavelength of 274 nm)(2-[4,6-diphenyl-1,3,5-triazine-2-yl]-5-(hexyloxy)phenol).

[Benzophenone-Based Ultraviolet Absorber]

Examples of the benzophenone-based ultraviolet absorber can includeCHIMASSORB 81/FL (manufactured by BASF, and having a molecular weight of326.4 and a melting point of 48 to 49° C.)(2-hydroxy-4-(octyloxy)benzophenone).

[Benzoate-Based Ultraviolet Absorber]

Examples of a benzoate-based ultraviolet absorber can include TINUVIN120 (manufactured by BASF, and having a molecular weight of 438.7, amelting point of 192 to 197° C., and a maximum absorption wavelength of265 nm) (2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate).

[Hindered Amine Stabilizer]

Examples of a hindered amine stabilizer can include: CHIMASSORB 2020FDL(manufactured by BASF, and having a molecular weight of 2600 to 3400 anda melting point of 130 to 136° C.) (polycondensate of dibutylamine1,3,5-triazineN,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamineN-(2,2,6,6-tetramethyl-4-piperidyl)butylamine); CHIMASSORB 944 FDL(manufactured by BASF, and having a molecular weight of 2000 to 3100 anda melting point of 100 to 135° C.) (poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{2,2,6,6-tetramethyl-4-piperidyl)imino}]); TINUVIN 622 LD (manufacturedby BASF, and having a molecular weight of 3100 to 4000 and a meltingpoint of 55 to 70° C.) (butanedioic acid1-[2-(4-hydroxy-2,2,6,6-tetramethyl-piperidino)ethyl]); TINUVIN 144(manufactured by BASF, and having a molecular weight of 685 and amelting point of 146 to 150° C.)(2-butyl-2-[3,5-di(tert-butyl)-4-hydroxybenzyl]malonic acidbis(1,2,2,6,6-pentamethyl-4-piperidyl); TINUVIN 292 (manufactured byBASF, and having a molecular weight of 509) (sebacic acidbis(1,2,2,6,6-pentamethyl-4-piperidinyl); and TINUVIN 770 DF(manufactured by BASF, and having a molecular weight of 481 and amelting point of 81 to 85° C.) (sebacic acidbis(2,2,6,6-tetramethylpiperidine-4-yl).

In the present invention, ultraviolet transmission is restrained byblending titanium oxide into the thermoplastic elastomer composition.Deterioration due to ultraviolet radiation can therefore be prevented.When blending titanium oxide into the thermoplastic elastomer, careshould be taken to achieve uniform dispersion in mixing because poordispersion may result in degraded durability.

Further, the elastomer composition preferably contains an antioxidant.The antioxidant can function as a radical supplementary agent to mainlysupplement a carbon radical, thereby preventing deterioration of themolecular chain of the polymer. In particular, it is preferable to usethe ultraviolet absorber and the antioxidant in combination. Examples ofthe antioxidant used in the present invention are listed below.

[Hindered Phenolic Antioxidant]

IRGANOX 1010 (manufactured by BASF); ADK STAB AO-60 (manufactured byADEKA Corporation); SUMILIZER BP-101 (manufactured by Sumitomo ChemicalCo., Ltd.) (pentaerythrityltetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]); IRGANOX 1035(manufactured by BASF)(2,2-thio-diethylenebis[(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)]); IRGANOX 1076 (manufactured by BASF)(octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate); IRGANOX 1098(manufactured by BASF)(N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide);IRGANOX 1135 (manufactured by BASF)(isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate]); IRGANOX 1330(manufactured by BASF)(1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene);IRGANOX 1726 (manufactured by BASF)(4,6-bis(dodecylthiomethyl)-O-cresol); IRGANOX 1425 (manufactured byBASF) (bis(3,5-di-t-butyl-4-hydroxybenzylphosphonic acid ethyl) calcium(50%), polyethylene wax (50%)); IRGANOX 1520 (manufactured by BASF)(2,4-bis[(octylthio)methyl]-O-cresol); IRGANOX 245 (manufactured byBASF) (triethyleneglycol-bis[(3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate)]); IRGANOX 259 (manufactured by BASF)(1,6-hexanediol-bis[(3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate]);IRGANOX 3114 (manufactured by BASF)(tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate); IRGANOX 5057(manufactured by BASF) (octylated diphenylamine); IRGANOX 565(manufactured by BASF)(2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine);Cyanox CY1790 (manufactured by Sun Chemical Company Ltd.)(1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid);ADK STAB AO-40 (manufactured by ADEKA Corporation); SUMILIZER BBM(manufactured by Sumitomo Chemical Co., Ltd.)(4,4′-butylidenebis(3-methyl-6-t-butylphenol); ADK STAB AO-50(manufactured by ADEKA Corporation); SUMILIZER BP-76 (manufactured bySumitomo Chemical Co., Ltd.) (stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate); ADK STAB AO-80 (manufactured by ADEKA Corporation);SUMILIZER GA-80 (manufactured by Sumitomo Chemical Co., Ltd.)(3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]-undecane).

[Phosphorus-Based Antioxidant]

A phosphorus-based antioxidant is used as a peroxide decompositionagent, and has an excellent function of preventing oxidation duringthermal process molding. Examples thereof are listed below.

IRGAFOS12 (manufactured by BASF, and having a molecular weight of1462.9)(6,6′,6″-[nitrilotris(ethyleneoxy)]tris(2,4,8,10-tetra-tert-butylbenzo[d,f][1,3,2]dioxaphosphepin));IRGAFOS 38 (manufactured by BASF, and having a molecular weight of 514)(phosphorous acid ethylbis(2,4-di-tert-butyl-6-methylphenyl));IRGAFOS168 (manufactured by BASF, and having a molecular weight of 646);ADK STAB 2112 (manufactured by ADEKA Corporation); SUMILIZER P-16(manufactured by Sumitomo Chemical Co., Ltd.)(tris(2,4-di-t-butylphenyl)phosphite); ADK STAB PEP-8 (manufactured byADEKA Corporation) (distearyl pentaerythritol diphosphite); ADK STABPEP-36 (manufactured by ADEKA Corporation) (cyclicneopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl)phosphite).

[Hydroxylamine-Based]

IRGASTAB FS 042 (manufactured by BASF) (N,N-dioctadecylhydroxylamine)

[Hindered Phenol/Phosphorus Mixture-Based Antioxidant]

IRGANOX B 225 (manufactured by BASF) (IRGAFOS168: IRGANOX 1010=1:1);IRGANOX 215 (manufactured by BASF) (IRGAFOS168: IRGANOX 1010=2:1);IRGANOX 220 (manufactured by BASF) (IRGAFOS168: IRGANOX 1010=3:1);IRGANOX 921 (manufactured by BASF) (IRGAFOS168: IRGANOX 1076=2:1).

[Oxygen Absorbent]

In the present embodiment, the antioxidant includes an oxygen absorbent.As the oxygen absorbent, a typical oxygen absorbent having a capacity tocapture oxygen in the air can be used. Examples thereof can include aniron powder oxygen absorbent that absorbs oxygen in the air by way ofoxidizing reaction of iron powder. Commonly used is a combination of 100parts by weight of iron powder having a surface area of more than orequal to 0.5 m²/g and 0.1 to 50 parts by weight of a halogenated metal,for example, a halide such as a chloride, a bromide, or an iodide of analkali metal or an alkaline earth metal, such as sodium chloride, sodiumbromide, calcium chloride, or magnesium chloride. This may be a mixturethereof, or may be obtained by coating the surface of iron powder withthe halogenated metal.

It is noted that porous particles, such as zeolite, impregnated withmoisture can be further combined with the oxygen absorbent used in thepresent embodiment to further promote the aforementioned oxidation ofiron by oxygen. In particular, a hindered phenolic antioxidant ispreferable as a radical trap agent for a carbon radical.

In the present embodiment, at least one or two or more of theabove-mentioned ultraviolet absorbers and antioxidants can be used incombination. In particular, it is preferable to use a benzotriazol-basedultraviolet absorber and a hindered phenolic antioxidant in combination.

[Blending Quantity of Ultraviolet Absorber/Antioxidant]

The elastomer composition containing a styrene-isobutylene-styrene blockcopolymer is likely to suffer from deterioration in a wavelength rangeof an ultraviolet wavelength of more than or equal to 290 nm. Thus, byblending an ultraviolet absorber with the elastomer composition, lighthaving a wavelength of around 320 nm to 350 nm where deterioration ismost likely to occur is absorbed and converted into harmless vibrationalenergy or thermal energy, thereby protecting the elastomer compositionfrom ultraviolet light. Here, the ultraviolet absorber includes a lightstabilizer.

On the other hand, in the elastomer composition, a radical is produceddue to flex fatigue during driving of the tire. The radical induces amain chain and linked deterioration proceeds, which is likely to causeoccurrence of cracks and destruction in the elastomer composition. Thus,by blending an antioxidant with the elastomer composition, theantioxidant has a function of supplementing the radical produced by flexfatigue to prevent deterioration.

In the present embodiment, the elastomer composition of the first layercontains at least one of an ultraviolet absorber and an antioxidant, andthe total blending quantity thereof ranges from 0.5 to 40% by mass ofthe elastomer component. When the blending quantity is less than 0.5% bymass, the effect of preventing deterioration by ultraviolet light andpreventing oxidation deterioration by oxygen cannot be achieved. On theother hand, when the blending quantity is more than 40% by mass,durability of the elastomer composition may deteriorate. The ultravioletabsorber and the antioxidant are preferably in a range of 2.0 to 20% bymass of the elastomer component.

<Composite Layer of First Layer and Second Layer>

In the present embodiment, the inner layer is composed of a compositelayer of the first layer and the second layer. Here, the first layer andthe second layer are thermoplastic elastomer compositions, and are in asoftened state in a mold at a vulcanization temperature, for example150° C. to 180° C. In the softened state, the thermoplastic elastomer isin an intermediate state between a solid and a liquid with improvedmolecular mobility. Further, since the thermoplastic elastomer in thesoftened state has an improved reactivity than in the solid state, itadheres to or is bonded with an adjacent member. Accordingly, in orderto manufacture a tire, a cooling step is required to prevent a change inthe shape of the thermoplastic elastomer and its adhesion or fusion tothe adjacent member. In the cooling step, the inside of a bladderportion can be cooled rapidly to 50 to 120° C. for 10 to 300 secondsafter vulcanization of the tire. As a cooling medium, at least oneselected from air, steam, water, and oil is used. By adopting such acooling step, a thin inner liner of 0.9 mm or less is easily formed.

Next, the state of arrangement of the inner liner with respect to thecarcass ply in a vulcanized tire will be shown in FIG. 9. In FIG. 9( a),composite layer PL is composed of first layer PL1 and second layer PL2.When composite layer PL is used as the inner liner of the pneumatictire, if second layer PL2 is arranged toward the tire radial outer sideso as to contact carcass ply C, adhesive strength between second layerPL2 and carcass C can be enhanced in the tire vulcanization step. Theresultant pneumatic tire has excellent air permeation resistance, sincethe inner liner is satisfactorily bonded with the rubber layer ofcarcass ply C.

<Method for Manufacturing Pneumatic Tire>

As a method for manufacturing the pneumatic tire in accordance with thepresent invention, a conventional manufacturing method can be used. Aninner liner is manufactured using composite layer PL. The inner liner isused for a green tire for pneumatic tire 11 and vulcanization-moldedtogether with other members, and thereby the pneumatic tire ismanufactured. When composite layer PL is arranged in the green tire,second layer PL2 of composite layer PL is arranged toward the tireradial outer side so as to contact carcass ply C. With such anarrangement, adhesive strength between second layer PL2 and carcass 6can be enhanced in the tire vulcanization step. The resultant pneumatictire can have excellent air permeation resistance, since the inner lineris satisfactorily bonded with the rubber layer of carcass ply C.

Example 1 Polymer Laminate

The first layer and the second layer used for the inner liner inaccordance with the present invention were manufactured to haveformulations shown in Tables 1 and 2 and used to manufacture a polymerlaminate. Polymer components and blended components used herein arelisted below.

[SIBS]

“SIBSTAR 102 (having a Shore A hardness of 25, a styrene componentcontent of 25% by mass, and a weight-average molecular weight of100,000)” manufactured by Kaneka Corporation was used.

The SIBS, a polymer mixture component, and an organic derivative of aclay mineral or inorganic clay mineral were charged into a twin-screwextruder (screw diameter: φ50 mm; L/D: 30; cylinder temperature: 220°C.) in accordance with the formulations shown in Tables 1 and 2 toobtain pellets.

[SIS]

D1161JP (having a styrene component content of 15% by mass and aweight-average molecular weight of 150,000) manufactured by KratonPerformance Polymers Inc. was used.

[SIB]

In a 2 L reaction vessel equipped with a stirrer, 589 mL ofmethylcyclohexane (dried with molecular sieves), 613 ml of n-butylchloride (dried with molecular sieves), and 0.550 g of cumyl chloridewere charged. After cooling the reaction vessel to −70° C., 0.35 mL ofα-picoline (2-methylpyridine) and 179 mL of isobutylene were added.Further, 9.4 mL of titanium tetrachloride was added to startpolymerization, and then the solution was reacted for 2.0 hours whilebeing stirred at −70° C. Next, 59 mL of styrene was added into thereaction vessel and the reaction was continued for another 60 minutes,and then the reaction was terminated by adding a large amount ofmethanol. After removing the solvent and the like from the reactionsolution, a polymer was dissolved in toluene and washed twice withwater. This toluene solution was added to the methanol mixture, therebyprecipitating the polymer, and the resultant polymer was dried at 60° C.for 24 hours to obtain a styrene-isobutylene diblock copolymer (having astyrene component content of 15% by mass and a weight-average molecularweight of 70,000).

[Polyamide-Based Polymer]

“UBESTA XPA 9040 (having a Shore D hardness of 40)” manufactured by UbeIndustries, Ltd.

[Ethylene-Vinyl Alcohol Copolymer]

“EVAL E105” manufactured by KURARAY CO., LTD.

[Chlorobutyl]

“Exxon Chlorobutyl 1068” manufactured by Exxon Mobil Corporation

[Natural Rubber (NR)]

TSR20

Carbon black: “SEAST V” (N660, N₂SA: 27 m²/g) manufactured by TokaiCarbon Co., Ltd.

Organic derivative of a clay mineral: “BENTONE 34” manufactured by PheoxCo. was used. Its layered clay mineral is a hectorite clay mineral, itsorganic compound is dimethyldistearylammonium salt, and the cationexchange amount of the organic compound is 100 meg/100 g.

Inorganic clay mineral: “Kunipia F” manufactured by KUNIMINE INDUSTRIESCO., LTD.

TABLE 1 Example Example Example Example Example Example 1-1 1-2 1-3 1-41-5 1-6 Laminate First layer SIBS [phr] 90 90 90 90 90 90 structure/Polyamide-based polymer [phr] 10 10 10 10 10 10 FormulationEthylene-vinyl alcohol copolymer [phr] — — — — — — Chlorobutyl [phr] — —— — — — NR [phr] — — — — — — Organic derivative of a clay mineral [phr]0.1 0.1 0.1 30 30 30 Inorganic clay mineral [phr] — — — — — — Carbon[phr] — — — — — — Thickness of SIBS layer [mm] 0.25 0.25 0.25 0.25 0.250.25 Second layer SIS [phr] 100 — 100 100 — 100 SIB [phr] — 100 — — 100— Thickness of SIS layer [mm] 0.05 — 0.05 0.05 — 0.05 Thickness of SIBlayer [mm] — 0.05 — — 0.05 — Inner liner dimension [mm] 1300 1300 13001300 1300 1300 Carcass ply Ply dimension [mm] 1250 800 800 1250 800 800Displaced amount between inner liner and 50 500 250 50 500 250 carcassply in width direction [mm] Evaluation Presence/absence of air-inportions A A A A A A Flex crack growth index 119 118 119 126 125 122Rolling resistance index 117 117 118 116 115 117 Static air pressuredrop rate (%) 2.3 2.4 2.2 1.8 1.8 1.7 Overall judgment A A A A A AUniformity 121 122 122 123 122 121 Example Example Example ExampleExample Example 1-7 1-8 1-9 1-10 1-11 1-12 Laminate First layer SIBS[phr] 90 90 90 70 70 70 structure/ Polyamide-based polymer [phr] 10 1010 10 10 10 Formulation Ethylene-vinyl alcohol copolymer [phr] — — — 2020 20 Chlorobutyl [phr] — — — — — — NR [phr] — — — — — — Organicderivative of a clay mineral [phr] 50 50 50 30 30 30 Inorganic claymineral [phr] — — — — — — Carbon [phr] — — — — — — Thickness of SIBSlayer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 Second layer SIS [phr] 100 —100 100 — 100 SIB [phr] — 100 — — 100 — Thickness of SIS layer [mm] 0.05— 0.05 0.05 — 0.05 Thickness of SIB layer [mm] — 0.05 — — 0.05 — Innerliner dimension [mm] 1300 1300 1300 1300 1300 1300 Carcass ply Plydimension [mm] 1250 800 800 1250 800 800 Displaced amount between innerliner and 50 500 250 50 500 250 carcass ply in width direction [mm]Evaluation Presence/absence of air-in portions A A A A A A Flex crackgrowth index 135 133 134 122 121 123 Rolling resistance index 116 115115 114 115 115 Static air pressure drop rate (%) 1.7 1.6 1.5 1.9 1.81.8 Overall judgment A A A A A A Uniformity 122 123 122 121 122 123

TABLE 2 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. ex.*ex. ex. ex. ex. ex. ex. ex. ex. ex. 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-91-10 Laminate First SIBS [phr] — 90 90 90 50 100 — — 90 90 structure/layer Polyamide-based — 10 10 10 50 — 100 — 10 10 Formu- polymer [phr]lation Ethylene-vinyl alcohol — — — — — — — 100 — — copolymer [phr]Chlorobutyl [phr] 80 — — — — — — — — — NR [phr] 20 — — — — — — — — —Organic derivative of a clay — — — — 30 30 30 30 — — mineral [phr]Inorganic clay mineral [phr] — 0.1 0.1 0.1 — — — — — — Carbon [phr] 60 —— — — — — — — — Thickness of SIBS layer [mm] 0.25 0.25 0.25 0.25 0.250.25 0.25 0.25 0.25 0.25 Second SIS [phr] 100 100 — 100 100 100 100 100100 100 layer SIB [phr] — — 100 — — — — — — — Thickness of SIS layer[mm] 0.05 0.05 — 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Thickness of SIBlayer [mm] — — 0.05 — — — — — — — Inner liner dimension [mm] 1300 13001300 1300 1300 1300 1300 1300 1300 1300 Carcass Ply dimension [mm] 12501300 1260 700 1250 1250 1250 1250 1250 1250 ply Displaced amount betweeninner 50 0 49 600 50 50 50 50 50 50 liner and carcass ply in widthdirection [mm] Evalu- Presence/absence of air-in portions C C C C C C CC C C ation Flex crack growth index 100 102 100 99 98 99 99 99 89 88Rolling resistance index 100 99 99 98 99 99 98 99 99 99 Static airpressure drop rate (%) 2.9 2.9 2.8 2.9 2.7 2.7 2.8 2.9 3.1 3.2 Overalljudgment B B B B B B B B B B Uniformity 100 97 97 98 96 99 98 97 99 98*Comp. ex.: Comparative example

Various compounding agents were added to the polymer component toprepare a composition. The following compounding agents were used. Forthe first layer and the second layer, common compounding agents shown inTable 3 were used.

TABLE 3 Compounding agents phr. Stearic acid 3 Zinc oxide 5 Ageinhibitor 1 Vulcanization accelerator 1 Sulfur 0.5

stearic acid: “Stearic Acid Lunac S30” manufactured by Kao Corporation

zinc oxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining &Smelting Co., Ltd.

age inhibitor: “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd.

vulcanization accelerator: “Nocceler DM” manufactured by Ouchi ShinkoChemical Industrial Co., Ltd.

sulfur: “Sulfur Powder” manufactured by Tsurumi Chemical Industry Co.,Ltd.

<Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step described above. Pneumatic tires of examples andcomparative examples as indicated in detail in Tables 1 and 2 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8.

In Examples 1-1 to 1-3, the inner liner had a first layer which was amixed system of the SIBS and a polyamide-based polymer blended with 0.1parts by mass of the organic derivative of a clay mineral, and a secondlayer made of the SIS or the SIB, and a displaced distance between theinner liner and the carcass was 50 mm, 500 mm, and 250 mm, respectively.

In Examples 1-4 to 1-6, the inner liner had a first layer which was amixed system of the SIBS and the polyamide-based polymer blended with 30parts by mass of the organic derivative of a clay mineral, and a secondlayer made of the SIS or the SIB, and the displaced distance between theinner liner and the carcass was 50 mm, 500 mm, and 250 mm, respectively.

In Examples 1-7 to 1-9, the inner liner had a first layer which was amixed system of the SIBS and the polyamide-based polymer blended with 50parts by mass of the organic derivative of a clay mineral, and a secondlayer made of the SIS or the SIB, and the displaced distance between theinner liner and the carcass was 50 mm, 500 mm, and 250 mm, respectively.

In Examples 1-10 to 1-12, the inner liner has a first layer which was amixed system of the SIBS, the polyamide-based polymer, and anethylene-vinyl alcohol copolymer blended with 30 parts by mass of theorganic derivative of a clay mineral, and a second layer made of the SISor the SIB, and the displaced distance between the inner liner and thecarcass was 50 mm, 500 mm, and 250 mm, respectively.

In Comparative Example 1-1, the inner liner had a first layer which wasa mixed system of chlorobutyl and NR. Comparative Examples 1-2 to 1-4are cases where the first layer of the inner liner was blended with aninorganic clay mineral, and the displaced distance was varied.Comparative Examples 1-6 to 1-8 are cases where formulations of thepolymers in the first layer were outside the scope of present invention.Comparative Examples 1-9, 1-10 are cases where the first layer was notblended with the organic derivative of a clay mineral.

Examples 1-1 to 1-12 are all excellent in overall judgment on air-inperformance, flex crack growth, rolling resistance properties, andstatic air pressure drop rate, as well as tire uniformity.

<Performance Test>

Performance evaluation was performed on the pneumatic tires manufacturedas described above, in the following manner.

<Air-in Performance>

The inside of each vulcanized tire was examined by appearance, andevaluated as follows:

A: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less and the number of air-in portions with adiameter of more than 5 mm were both 0.

B: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less was one to three, and the number of air-inportions with a diameter of more than 5 mm was 0.

C: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less was four or more, and the number of air-inportions with a diameter of more than 5 mm was one or more.

<Flex Crack Growth Test>

A flex crack growth test was performed to make an evaluation based onwhether the inner liner was broken or peeled off. Each prototype tirewas mounted on a JIS standard rim 15×6JJ, and the inside of the tire wasmonitored under the conditions of a tire internal pressure of 150 KPa,which is lower than usual, a load of 600 kg, a speed of 100 km/hour, anda driving distance of 20,000 km, to measure the number of cracked/peeledportions. The obtained value was expressed as an index by the followingequation, for flex crack growth in each example and comparative example,using the value in Comparative Example 1-1 as a reference value. Itshows that the greater the value, the smaller the flex crack growth.

flex crack growth index=(the number of cracked portions in ComparativeExample 1-1)/(the number of cracked portions in each example andcomparative example)×100

<Rolling Resistance Index>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, androlling resistance was measured while driving the tire at roomtemperature (30° C.) under the conditions of a load of 3.4 kN, an airpressure of 230 kPa, and a speed of 80 km/hour, using a rollingresistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, a rolling resistance change rate (%) ineach example and comparative example was expressed as an index, usingthe value in Comparative Example 1-1 as a reference value 100. It showsthat the greater the rolling resistance change rate, the smaller therolling resistance.

rolling resistance index=(rolling resistance in Comparative Example1-1)/(rolling resistance in each example and comparative example)×100

<Static Air Pressure Drop Rate>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, and airwas sealed therein at an initial air pressure of 300 kPa. Then, the tirewas left at room temperature for 90 days and thereafter an air pressuredrop rate was calculated. The smaller the value, the less likely the airpressure is to be reduced, which is preferable.

<Uniformity (RFV)>

In conformity with the “Method for Testing Uniformity of AutomobileTire” of JASOC607:2000, radial force variation (RFV) was measured. Arelative value obtained by assuming the value in Comparative Example 1-1as 100 was expressed as an index. The greater the index, the moreexcellent the uniformity. Measurement was performed under the conditionsof a rim of 8.0×17, a tire rotation speed of 60 rpm, an air pressure of200 kPa, and a longitudinal load of 4000 kN.

<Overall Judgment>

Judgment A is made when all of the following conditions are satisfied:

(a) Air-in performance is evaluated as A

(b) Flex crack growth is evaluated as 100 or more

(c) Rolling resistance change rate is 100 or more

(d) Static air pressure drop rate (%/month) is 2.6 or less Judgment B ismade when one of the following conditions is satisfied. If a pluralityof judgments were made, a judgment with lower evaluation was adopted.

(a) Air-in performance is evaluated as B or C

(b) Flex crack growth is evaluated as being less than 100

(c) Rolling resistance change rate is less than 100

(d) Static air pressure drop rate (%/month) is 2.7 or more Example 2

<Manufacturing of Inner Liner>

Various compounding agents were charged into a twin-screw extruder(screw diameter: φ50 mm; L/D: 30; cylinder temperature: 220° C.) inaccordance with formulations shown in Tables 4 and 5 to obtain pellets.The pellets were extruded as a sheet using an extruder (screw diameter:φ80 mm; L/D: 50; die gap width: 40 mm; cylinder temperature: 220° C.),at a screw rotation number of 80 RPM and an extrusion speed of about 9m/minute.

TABLE 4 Example Example Example Example Example Example 2-1 2-2 2-3 2-42-5 2-6 Laminate First layer IIR/NR (*1) — — — — — — structure/ Filler(*2) — — — — — — Formulation SIBS (*3) 99.5 99.5 99.5 99.5 99.5 99.5Polybutene (*4) 0.5 0.5 0.5 0.5 0.5 0.5 Naphthenic oil (*5) — — — — — —Layer thickness [mm] 0.2 0.2 0.2 0.2 0.2 0.2 Second-a layer SIS [phr](*6) 100 100 100 99.5 99.5 99.5 SIB [phr] (*7) — — — — — — Polybutene(*4) — — — 0.5 0.5 0.5 Naphthenic oil (*5) — — — — — — Layer thickness[mm] 0.05 0.05 0.05 0.05 0.05 0.05 Second-b layer SIS [phr] (*6) — — — —— — SIB [phr] (*7) 100 100 100 99.5 99.5 99.5 Polybutene (*4) — — — 0.50.5 0.5 Naphthenic oil (*5) — — — — — — Layer thickness [mm] 0.05 0.050.05 0.05 0.05 0.05 Inner liner dimension [mm] 1300 1300 1300 1300 13001300 Carcass ply Ply dimension [mm] 1250 800 800 1250 800 800 Displacedamount between inner liner and 50 500 250 50 500 250 carcass ply inwidth direction [mm] Evaluation Vulcanization adhesive strength index115 116 115 121 122 123 Presence/absence of air-in portions A A A A A AFlex crack growth index 129 128 129 133 135 133 Rolling resistance index117 117 118 116 115 117 Static air pressure drop rate (%) 1.9 1.8 1.91.9 1.8 1.9 Uniformity 108 110 110 111 114 115 Example Example ExampleExample Example Example 2-7 2-8 2-9 2-10 2-11 2-12 Laminate First layerIIR/NR (*1) — — — — — — structure/ Filler (*2) — — — — — — FormulationSIBS (*3) 60 60 60 100 100 100 Polybutene (*4) 40 40 40 — — — Naphthenicoil (*5) — — — — — — Layer thickness [mm] 0.2 0.2 0.2 0.2 0.2 0.2Second-a layer SIS [phr] (*6) 100 100 100 60 60 60 SIB [phr] (*7) — — —— — — Polybutene (*4) — — — 40 40 40 Naphthenic oil (*5) — — — — — —Layer thickness [mm] 0.05 0.05 0.05 0.05 0.05 0.05 Second-b layer SIS[phr] (*6) — — — — — — SIB [phr] (*7) 100 100 100 60 60 60 Polybutene(*4) — — — 40 40 40 Naphthenic oil (*5) — — — — — — Layer thickness [mm]0.05 0.05 0.05 0.05 0.05 0.05 Inner liner dimension [mm] 1300 1300 13001300 1300 1300 Carcass ply Ply dimension [mm] 1250 800 800 1250 800 800Displaced amount between inner liner and 50 500 250 50 500 250 carcassply in width direction [mm] Evaluation Vulcanization adhesive strengthindex 122 121 122 111 112 112 Presence/absence of air-in portions A A AA A A Flex crack growth index 130 131 134 130 129 129 Rolling resistanceindex 116 115 115 114 115 115 Static air pressure drop rate (%) 2.4 2.42.3 2.4 2.4 2.4 Uniformity 118 115 115 114 115 115

TABLE 5 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp.Comp. ex.* ex. ex. ex. ex. ex. ex. ex. ex. ex. ex. 2-1 2-2 2-3 2-4 2-52-6 2-7 2-8 2-9 2-10 2-11 Lami- First IIR/NR (*1) 95 — — — — — — — — — —nate layer Filler (*2) 60 — — — — — — — — — — struc- SIBS (*3) — 99.599.5 99.5 100 100 95 95 99.5 60 100 ture/ Polybutene (*4) — 0.5 0.5 0.5— — — — 0.5 40 — Formu- Naphthenic oil (*5) 5 — — — — — 5 5 — — — lationLayer thickness 0.5 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.5 0.5 0.5 [mm]Second-a SIS [phr] (*6) — 99.5 99.5 99.5 100 — 95 — — — — layer SIB[phr] (*7) — — — — — 100 — 95 — — — Polybutene (*4) — 0.5 0.5 0.5 — — —— — — — Naphthenic oil (*5) — — — — — — 5 5 — — — Layer thickness — 0.050.05 0.05 0.05 0.05 0.05 0.05 — — — [mm] Second-b SIS [phr] (*6) — — — —— — — — — — — layer SIB [phr] (*7) — 99.5 99.5 99.5 100 100 95 95 — — —Polybutene (*4) — 0.5 0.5 0.5 — — — — — — — Naphthenic oil (*5) — — — —— — 5 5 — — — Layer thickness — 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 0.05 [mm] Inner liner dimension [mm] 1300 1300 1300 1300 1300 13001300 1300 1300 1300 1300 Carcass Ply dimension [mm] 1250 1300 1260 7001250 1250 1250 1250 1250 1250 1250 ply Displaced amount between 50 0 49600 50 50 50 50 50 50 50 inner liner and carcass ply in width direction[mm] Evalu- Vulcanization adhesive strength 100 109 108 107 50 55 36 3540 40 41 ation index Presence/absence of air-in portions B C C C C C C CC C C Flex crack growth index 100 101 99 95 100 102 101 102 102 101 102Rolling resistance index 100 101 102 102 99 100 100 101 98 97 96 Staticair pressure drop rate (%) 4.3 2.6 2.6 2.5 2.7 2.6 2.6 2.7 3.2 3.2 3.2Uniformity 100 96 98 96 96 95 97 98 95 94 96 *Comp. ex.: Comparativeexample (*1) IIR: “Exxon Chlorobutyl 1068” manufactured by Exxon MobilCorporation (*2) carbon: “SEAST V” (N660, N₂SA: 27 m²/g) manufactured byTokai Carbon Co., Ltd. (*3) SIRS: “SIBSTAR 102T (having a Shore Ahardness of 25 and a styrene content of 25% by mass)” manufactured byKaneka Corporation (*4) polybutene: “Nisseki Polybutene Grade HV300”(having a number-average molecular weight of 300) manufactured by NipponOil Corporation (*5) naphthenic oil: “Diana Process Oil NM280”manufactured by Idemitsu Kosan Co., Ltd. (*6) SIS: “D1161JP” (astyrene-isoprene-styrene triblock copolymer having a weight-averagemolecular weight of 150,000 and a styrene unit content of 15% by mass)manufactured by Kraton Performance Polymers Inc. (*7) SIB:

In a 2 L reaction vessel equipped with a stirrer, 589 mL ofmethylcyclohexane (dried with molecular sieves), 613 ml of n-butylchloride (dried with molecular sieves), and 0.550 g of cumyl chloridewere charged. After cooling the reaction vessel to −70° C., 0.35 mL ofα-picoline (2-methylpyridine) and 179 mL of isobutylene were added.Further, 9.4 mL of titanium tetrachloride was added to startpolymerization, and then the solution was reacted for 2.0 hours whilebeing stirred at −70° C. Next, 59 mL of styrene was added into thereaction vessel and the reaction was continued for another 60 minutes,and then the reaction was terminated by adding a large amount ofmethanol. After removing the solvent and the like from the reactionsolution, a polymer was dissolved in toluene and washed twice withwater. This toluene solution was added to the methanol mixture, therebyprecipitating the polymer, and the resultant polymer was dried at 60° C.for 24 hours to obtain a styrene-isobutylene diblock copolymer.

Styrene component content: 15% by mass

Weight-average molecular weight: 70,000

It is noted that the formulations shown in Tables 4 and 5 are expressedassuming the sum of the IIR/NR, the SIBS, polybutene, and naphthenic oilas 100 parts by mass. The blending quantity of the filler is expressedby a blending part in a case where the sum of the polymer components isassumed as 100 parts by mass.

<Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step described above. Pneumatic tires of examples andcomparative examples as indicated in detail in Tables 4 and 5 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8.

In the examples, a displaced distance (amount) L was changed to 50 mm,500 mm, or 250 mm by setting the dimension of the inner liner to 1300 mmand changing the dimension of the carcass ply, with reference to FIG. 5.

<Performance Test>

Performance evaluation was performed on the pneumatic tires manufacturedas described above, in the following manner.

(a) Vulcanization Adhesive Strength of First Layer

The first layer and the unvulcanized rubber sheet were bonded together,and were heated at 170° C. for 20 minutes to fabricate a sample formeasuring vulcanization adhesive strength. A peel-off strength wasmeasured by a tensile peel test as vulcanization adhesive strength. Theobtained value was expressed as an index by the following equation, forvulcanization adhesive strength of the first layer in each example andeach comparative example, using the value in Comparative Example 2-1 asa reference value (100). It shows that the greater the value, thegreater the vulcanization adhesive strength, which is preferable.

(vulcanization adhesive strength index)=(vulcanization adhesive strengthin each example and each comparative example)/(vulcanization adhesivestrength in Comparative Example 2-1)×100

(b) Presence or Absence of Air-in Portions

The inside of each vulcanized tire was examined, and evaluated on thefollowing criteria:

A: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less and the number of air-in portions with adiameter of more than 5 mm were both 0.

B: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less was one to three, and the number of air-inportions with a diameter of more than 5 mm was 0.

C: In appearance, per tire, the number of air-in portions with adiameter of 5 mm or less was four or more, or the number of air-inportions with a diameter of more than 5 mm was one or more.

(c) Flex Crack Growth Test

A flex crack growth test was performed to make an evaluation based onwhether the inner liner was broken or peeled off. Each prototype tirewas mounted on a JIS standard rim 15×6JJ, and the inside of the tire wasmonitored under the conditions of a tire internal pressure of 150 KPa,which is lower than usual, a load of 600 kg, a speed of 100 km/hour, anda driving distance of 20,000 km, to measure the number of cracked/peeledportions. The obtained value was expressed as an index by the followingequation, for flex crack growth in each example and comparative example,using the value in Comparative Example 2-1 as a reference value. Itshows that the greater the value, the smaller the flex crack growth.

flex crack growth index=(the number of cracked portions in ComparativeExample 2-1)/(the number of cracked portions in each example and eachcomparative example)×100

(d) Rolling Resistance Index

Each prototype tire was mounted on a JIS standard rim 15×6JJ, androlling resistance was measured while driving the tire at roomtemperature (30° C.) under the conditions of a load of 3.4 kN, an airpressure of 230 kPa, and a speed of 80 km/hour, using a rollingresistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, a rolling resistance change rate (%) ineach example was expressed as an index, using the value in ComparativeExample 2-1 as a reference value (100). It shows that the greater therolling resistance change rate, the smaller the rolling resistance.

rolling resistance index=(rolling resistance in Comparative Example2-1)/(rolling resistance in each example and each comparativeexample)×100

(e) Static Air Pressure Drop Rate

Each prototype tire was mounted on a JIS standard rim 15×6JJ, and airwas sealed therein at an initial air pressure of 300 kPa. Then, the tirewas left at room temperature for 90 days and thereafter an air pressuredrop rate was calculated. The smaller the value, the less likely the airpressure is to be reduced, which is preferable.

(f) Uniformity

In conformity with the “Method for Testing Uniformity of AutomobileTire” of JASOC607:2000, radial force variation (RFV) was measured usinga tire uniformity tester. A relative value obtained by assuming thevalue in Comparative Example 2-1 as 100 was expressed as an index. Thegreater the index, the more excellent the uniformity. Measurement wasperformed under the conditions of a rim of 8.0×17, a tire rotation speedof 60 rpm, an air pressure of 200 kPa, and a longitudinal load of 4000kN.

<Evaluation Results>

Examples 2-1 to 2-3 are cases where the SIBS of the first layer wasblended with 0.5% by mass of a C4 polymer (polybutene), and Examples 2-4to 2-6 are cases where the SIBS of the first layer, a second-a layer,and a second-b layer were blended with 0.5% by mass of the C4 polymer(polybutene).

Examples 2-7 to 2-9 are cases where the SIBS of the first layer wasblended with 40% by mass of the C4 polymer (polybutene), and Examples2-10 to 2-12 are cases where the second-a layer and the second-b layerwere blended with 40% by mass of the C4 polymer (polybutene).

Comparative Example 2-1 is a case where IIR was used for the firstlayer. Comparative Examples 2-2 to 2-4 are cases where the first layer,the second-a layer, and the second-b layer were blended with the C4polymer (polybutene). However, in these comparative examples, thedisplaced amount between the width of the inner liner and the width ofthe carcass ply was outside the scope of the present invention.

Comparative Examples 2-5 to 2-8 are cases where the first layer, thesecond-a layer, and the second-b layer were not blended with the C4polymer (polybutene). Comparative Examples 2-9 to 2-11 are cases whereonly the first layer was used.

The examples of the present invention are all excellent in overalljudgment on air-in performance, flex crack growth, rolling resistanceproperties, and static air pressure drop rate.

Example 3

Hereinafter, a method for manufacturing a pneumatic tire in accordancewith the present invention will be described based on examples.

<Manufacturing of Inner Liner>

Various compounding agents were charged into a twin-screw extruder(screw diameter: φ50 mm; L/D: 30; cylinder temperature: 220° C.) inaccordance with formulations shown in Tables 6 and 7 to obtain pellets.The pellets were extruded as a sheet using an extruder (screw diameter:φ80 mm; L/D: 50; die gap width: 40 mm; cylinder temperature: 220° C.),at a screw rotation number of 80 RPM and an extrusion speed of about 9m/minute.

TABLE 6 Examples Comparative examples Polymer sheet (first layer)formulation 3-1 3-2 3-3 3-4 3-5 3-6 3-1 3-2 3-3 3-4 3-5 3-6 3-7Formulation IIR (*1) 60 — 77.5 — 95 — 100 — — 50 — 98 — (parts by mass)NR (*2) — 60 — 77.5 — 95 — — — — 50 0 98 SIBS (*3) 40 40 22.5 22.5 5 5 —100 100 50 50 2 2 Carbon black (*4) — — — — — — 50 — — — — — — Stearicacid (*5) 3 3 3 3 3 3 3 — 3 3 3 3 3 Zinc oxide (*6) 5 5 5 5 5 5 5 — 5 55 5 5 Age inhibitor (*7) 1 1 1 1 1 1 1 — 1 1 1 1 1 Vulcanizationaccelerator (*8) 1 1 1 1 1 1 1 — 1 1 1 1 1 Sulfur (*9) 0.5 0.5 0.5 0.50.5 0.5 0.5 — 0.5 0.5 0.5 0.5 0.5 Evaluation Mooney viscosity (ML₁₊₄,130° C.) 28 29 31 31 44 45 50 8 11 25 25 45 46 Index of unvulcanizationtack 60 66 76 83 96 102 100 10 10 50 54 99 102 strength with carcasslayer Index of vulcanization adhesive 80 86 93 97 99 101 100 10 10 51 54100 100 strength with carcass layer Index of weight saving effect 140140 125 125 110 110 100 210 210 150 150 101 101 Rolling resistance index106 106 105 105 103 102 100 110 110 105 105 100 101 Static air pressuredrop rate 2.2 2.2 2.2 2.2 2.5 2.5 4 2.4 2.3 2.7 3.1 3.8 4 (%/month)Overall judgment A A A A A A C C C C C B B Uniformity 110 110 109 113113 115 100 95 90 95 95 95 95

TABLE 7 Manufacturing examples Second layer formulation 1 2 3 4 5 6 7 89 10 11 12 13 14 15 16 Formula- SIS (*10) 100 100 — — — — 10 — — 10 — —80 80 5 85 tion SIB (*11) — — 100 100 — — — 10 — — 10 — — — — — (partsEpoxidized SBS (*12) — — — — 100 100 — — 10 — — 10 — — — — by mass)Natural rubber (*2) — — — — — — 90 90 90 — — — 20 — 95 — Butyl rubber(*1) — — — — — — — — — 90 90 90 — 20 — 15 Stearic acid (*5) — 3 — 3 — 33 3 3 3 3 3 3 3 3 3 Zinc oxide (*6) — 5 — 5 — 5 5 5 5 5 5 5 5 5 5 5 Ageinhibitor (*7) — 1 — 1 — 1 1 1 1 1 1 1 1 1 1 1 Vulcanization — 1 — 1 — 11 1 1 1 1 1 1 1 1 1 accelerator (*8) Sulfur (*9) — 0.5 — 0.5 — 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Evaluation Index of A A A A A A A AA A A A A A A A unvulcanization tack strength with carcass layer Indexof B A B A B A A A A A A A A A B B vulcanization adhesive strength withcarcass layer (*1) IIR: “Exxon Chlorobutyl 1066” manufactured by ExxonMobil Corporation (*2) NR: natural rubber TSR20 (*3) SIBS: “SIBSTAR102T” (a styrene-isobutylene-styrene triblock copolymer having aweight-average molecular weight of 100,000, a styrene unit content of15% by mass, and a Shore A hardness of 25) manufactured by KanekaCorporation (*4) carbon black: “SEAST V” (N660, nitrogen-adsorptionspecific surface area: 27 m²/g) manufactured by Tokai Carbon Co., Ltd.(*5) stearic acid: “Stearic Acid Lunac S30” manufactured by KaoCorporation (*6) zinc oxide: “Zinc White No. 1” manufactured by MitsuiMining & Smelting Co., Ltd. (*7) age inhibitor: “Noclac 6C”(N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine) manufactured byOuchi Shinko Chemical Industrial Co., Ltd. (*8) vulcanizationaccelerator: “Nocceler DM” (di-2-benzothiazolyldisulfide) manufacturedby Ouchi Shinko Chemical Industrial Co., Ltd. (*9) sulfur: “SulfurPowder” manufactured by Tsurumi Chemical Industry Co., Ltd. (*10) SIS:“D1161JP” (a styrene-isoprene-styrene triblock copolymer having aweight-average molecular weight of 150,000 and a styrene unit content of15% by mass) manufactured by Kraton Performance Polymers Inc. (*11) SIB:the SIB obtained by the (Manufacturing of SIB) described above (astyrene-isobutylene diblock copolymer having a weight-average molecularweight of 70,000 and a styrene unit content of 15% by mass) (*12)epoxidized SBS: “Epofriend A1020” (an epoxy-modifiedstyrene-butadiene-styrene copolymer having a weight-average molecularweight of 100,000 and an epoxy equivalent of 500) manufactured by DaicelChemical Industries, Ltd.

It is noted that the formulations shown in Tables 6 and 7 are expressedassuming the sum of the IIR/NR, the SIBS, the SIS, the SIB, and theepoxidized SBS as 100 parts by mass. The blending quantity of the filleris expressed by a blending part in a case where the sum of the polymercomponents is assumed as 100 parts by mass.

<Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step described above. Pneumatic tires of examples andcomparative examples as indicated in detail in Table 6 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8. Tables6 to 10 show formulations of the inner liner and methods of moldingtires, together with evaluation results on the tires. In the examples,displaced distance (amount) L was changed to 50 mm, 500 mm, or 250 mm bysetting the length of the inner liner to 1300 mm and changing thedimension of the carcass ply, with reference to FIG. 5.

Examples 3-1 to 3-6, Comparative Examples 3-1 to 3-7

Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-7 are cases wherea sheet of a polymer composition made of a mixture of the SIBS and arubber component (the first layer only) was used as an inner liner. Ineach of the examples and comparative examples, a tire was molded underthe following conditions:

thickness of the inner liner: 0.25 mm

length of the inner liner: 1300 mm

length of the carcass ply: 800 mm

displaced amount between the inner liner and the carcass ply in thewidth direction (mm): 250 mm

It is recognized that Examples 3-1 to 3-6 of the present invention aremore excellent in overall judgment on unvulcanization tack strengthindex, vulcanization adhesive strength index, rolling resistanceproperties, and static air pressure drop rate, as well as uniformity,than Comparative Example 3-1.

Examples 3-7 to 3-30, Comparative Examples 3-8 to 3-17

Examples 3-7 to 3-30 and Comparative Examples 3-8 to 3-17 are caseswhere a composite body of a polymer sheet (the first layer) and thesecond layer was used as an inner liner. In the row of the “First Layer”in Tables 8 to 10, “Example 3-1” indicates that the inner liner used inExample 3-1 was used as the first layer, and “Comparative Example 3-1”indicates that the inner liner used in “Comparative Example 3-1” wasused as the first layer. The same applies to other examples andcomparative examples.

The examples of the present invention are all excellent in overalljudgment on unvulcanization tack strength index, vulcanization adhesivestrength index, rolling resistance properties, and static air pressuredrop rate, as well as uniformity.

TABLE 8 Examples 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-16 3-173-18 Lami- First layer Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- Exam- Exam- Exam- nated ple ple ple ple ple ple ple ple ple pleple ple struc- 3-1 3-1 3-1 3-2 3-2 3-2 3-3 3-4 3-5 3-6 3-1 3-1 tureSecond layer Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg.ex.* 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 7 ex.10 Evalu- Thickness of first 0.25 0.25 0.25 0.25 0.25 0.25 0.25 ationlayer [mm] Thickness of second 0.05 0.05 0.05 0.05 0.05 0.05 0.05 layer[mm] Inner liner dimension 1300 1300 1300 1300 1300 1300 1300 length[mm] Ply dimension 1250 800 800 1250 800 800 800 length [mm] Displacedamount 50 500 250 50 500 250 250 between inner liner and carcass ply inwidth direction [mm] Mooney viscosity 28 28 28 29 28 29 34 38 44 45 3937 (ML₁₊₄, 130° C.) Index of 75 74 75 78 80 85 80 85 83 93 78 88unvulcanization tack strength between first and second layers Index of85 86 84 81 82 95 88 101 95 105 100 110 vulcanization adhe- sivestrength between first and second layers Index of weight saving 141 143140 140 139 140 125 125 110 110 140 140 effect Rolling resistance index105 103 104 104 103 106 105 105 103 102 104 105 Static air pressure drop2.1 2.1 2.2 2.1 2.1 2.2 2.2 2.2 2.5 2.5 2 1.9 rate (%/month) Overalljudgment A A A A A A A A A A A A Uniformity 118 120 125 120 123 125 128125 127 125 125 127 *Mfg. ex.: Manufacturing example

TABLE 9 Examples 3-19 3-20 3-21 3-22 3-23 3-24 3-25 3-26 3-27 3-28 3-293-30 Lami- First layer Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- Exam- Exam- Exam- nated ple ple ple ple ple ple ple ple ple pleple ple struc- 3-2 3-2 3-3 3-3 3-4 3-4 3-5 3-5 3-6 3-6 3-1 3-1 tureSecond layer Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. Mfg.ex.* 7 ex. 10 ex. 7 ex. 10 ex. 7 ex. 10 ex. 7 ex. 10 ex. 7 ex. 10 ex. 13ex. 14 Evalu- Thickness of first 0.25 ation layer [mm] Thickness ofsecond 0.05 layer [mm] Inner liner dimension 1300 length [mm] Plydimension length 800 [mm] Displaced amount 250 between inner liner andcarcass ply in width direction [mm] Mooney viscosity 39 37 42 41 42 4144 46 45 45 37 35 (ML₁₊₄, 130° C.) Index of 85 75 70 85 82 70 98 97 102102 75 85 unvulcanization tack strength between first and second layersIndex of 107 97 95 105 102 93 99 99 101 101 92 102 vulcanization adhe-sive strength between first and second layers Index of weight saving 140140 110 110 110 110 110 109 110 110 110 110 effect Rolling resistanceindex 103 104 103 104 102 103 103 104 102 103 105 106 Static airpressure 2.2 2 2.1 2 2.2 2 2.5 2.5 2.5 2.4 1.9 1.8 drop rate (%/month)Overall judgment A A A A A A A A A A A A Uniformity 128 130 131 130 128121 129 128 129 129 128 128 *Mfg. ex.: Manufacturing example

TABLE 10 Comparative examples 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-163-17 Laminated First layer Comp. Comp. Comp. Comp. Comp. Comp. Comp.Comp. Comp. Comp. structure ex.* ex. ex. ex. ex. ex. ex. ex. ex. ex. 3-13-2 3-3 3-4 3-5 3-6 3-7 3-1 3-1 3-1 Second layer Mfg. Mfg. Mfg. Mfg.Mfg. Mfg. Mfg. Mfg. Mfg. Mfg. ex.** 2 ex. 2 ex. 2 ex. 2 ex. 2 ex. 2 ex.7 ex. 2 ex. 2 ex. 2 Evaluation Thickness of first layer [mm] 0.25 0.250.25 0.25 Thickness of second layer [mm] 0.05 0.05 0.05 0.05 Inner linerdimension length [mm] 1300 1300 1300 1300 Ply dimension length [mm] 12501300 1260 700 Displaced amount between inner 50 0 40 600 liner andcarcass ply in width direction [mm] Mooney viscosity (ML₁₊₄, 130° C.) 5010 15 25 26 48 49 50 50 50 Index of unvulcanization tack strength 100 2020 45 45 95 105 100 111 112 between first and second layers Index ofvulcanization adhesive strength 100 20 20 45 50 99 109 100 98 100between first and second layers Index of weight saving effect 100 111112 112 114 116 117 100 100 100 Rolling resistance index 100 99 98 98 9999 99 96 96 96 Static air pressure drop rate (%/month) 4 2.5 2 3 3 3.93.9 4.5 4.5 4.5 Overall judgment C C C C C B B C C C Uniformity 90 90 9189 85 84 90 80 85 85 *Comp. ex.: Comparative example **Mfg. ex.:Manufacturing example

In Tables 6 to 10, a method for evaluating each inner liner (polymersheet) and pneumatic tire will be described below.

(a) Mooney Viscosity of the First Layer

In conformity with JISK 6300 “Method for Testing Unvulcanized Rubber”, aMooney viscosity tester “Mooney Viscometer SMV-202” manufactured byShimadzu Corporation was used, and a small rotor was rotated under thetemperature condition of 130° C. preheated for 1 minute, then, theMooney viscosity of the polymer composition after the lapse of 4 minutes(ML_(l+4), 130° C.) was measured. It shows that the smaller the Mooneyviscosity, the more excellent the workability.

(b1) Index of Unvulcanization Tack Strength with Carcass Layer

A sheet of a carcass layer (formulation: 100 parts by mass of astyrene-butadiene rubber, 50 parts by mass of carbon black, 2 parts bymass of sulfur, thickness: 2.0 mm) was prepared. The polymer sheet andthe sheet of the carcass layer were bonded together and held at 100 gffor 30 seconds, and a peel-off strength required to separate them wasmeasured as tack strength before vulcanization. For the first layer, thetack strength before vulcanization in each example and comparativeexample was expressed as an index by the following calculation equation,using the value in Comparative Example 3-1 as a reference value (100).It shows that the greater the index of tack strength beforevulcanization, the stronger the tack strength before vulcanization,which is preferable.

(index of tack strength before vulcanization)=(tack strength beforevulcanization in each example and comparative example)÷(tack strengthbefore vulcanization in Comparative Example 3-1)×100

For the second layer, a case where the second layer had a sufficienttack strength was evaluated as “A”, and a case where the second layerhad an insufficient tack strength was evaluated as “B”.

(b2) Index of Unvulcanization Tack Strength Between First and SecondLayers

The polymer sheets of the first and second layers were bonded togetherand held at 100 gf for 30 seconds. Then, a peel-off strength required toseparate them was measured as tack strength before vulcanization. Thetack strength before vulcanization in each example and comparativeexample was expressed as an index by the following calculation equation,using the value in Comparative Example 3-8 as a reference value (100).It shows that the greater the index of tack strength beforevulcanization, the stronger the tack strength before vulcanization,which is preferable.

(index of tack strength before vulcanization)=(tack strength beforevulcanization in each example and comparative example)÷(tack strengthbefore vulcanization in Comparative Example 3-8)×100

(c1) Vulcanization Adhesive Strength with Carcass Layer

The polymer sheet and the sheet of the carcass layer were bondedtogether and heated at 170° C. for 20 minutes to fabricate a sample formeasuring vulcanization adhesive strength. A peel-off strength wasmeasured by a tensile peel test as vulcanization adhesive strength. Thevulcanization adhesive strength in each example and comparative examplewas expressed as an index by the following calculation equation, usingthe value in Comparative Example 3-1 as a reference value (100). Itshows that the greater the index of vulcanization adhesive strength, thestronger the vulcanization adhesive strength, which is preferable.

(index of vulcanization adhesive strength)=(vulcanization adhesivestrength in each example and comparative example)÷(vulcanizationadhesive strength in Comparative Example 3-1)×100

For the second layer, a case where the second layer had a sufficientadhesive strength was evaluated as “A”, and a case where the secondlayer had an insufficient adhesive strength was evaluated as “B”.

(c2) Vulcanization Adhesive Strength Between First and Second Layers

The polymer sheets of the first and second layers were bonded togetherand heated at 170° C. for 20 minutes to fabricate a sample for measuringvulcanization adhesive strength. A peel-off strength was measured by atensile peel test as vulcanization adhesive strength. The vulcanizationadhesive strength in each example and comparative example was expressedas an index by the following calculation equation, using the value inComparative Example 3-8 as a reference value (100). It shows that thegreater the index of vulcanization adhesive strength, the stronger thevulcanization adhesive strength, which is preferable.

(index of vulcanization adhesive strength)=(vulcanization adhesivestrength in each example and comparative example)÷(vulcanizationadhesive strength in Comparative Example 3-8)×100

Further, evaluation of each pneumatic tire was performed based on thefollowing method.

(d) Index of Weight Saving Effect

The weight of a pneumatic tire in each example and comparative examplewas expressed as an index by the following calculation equation, usingthe value in Comparative Example 3-1 as a reference value (100) for thepneumatic tires in Examples 3-1 to 3-6 and Comparative Examples 3-1 to3-7, and using the value in Comparative Example 3-8 as a reference value(100) for the pneumatic tires in Examples 3-7 to 3-30 and ComparativeExamples 3-8 to 3-17. It shows that the greater the index of weightsaving effect, the lighter the tire weight, which is preferable.

(index of weight saving effect)=(tire weight in Comparative Example 3-1or Comparative Example 3-8)÷(tire weight in each example and comparativeexample)×100

(e) Rolling Resistance Index

Each manufactured pneumatic tire of 195/65R15 size was mounted on a JISstandard rim 15×6JJ, and rolling resistance was measured while drivingthe tire at room temperature (38° C.) under the conditions of a load of3.4 kN, an air pressure of 230 kPa, and a speed of 80 km/hour, using arolling resistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, rolling resistance in each example andcomparative example was expressed as an index, using the value inComparative Example 3-1 as a reference value (100) for the pneumatictires in Examples 3-1 to 3-6 and Comparative Examples 3-1 to 3-7, andusing the value in Comparative Example 3-8 as a reference value (100)for the pneumatic tires in Examples 3-7 to 3-30 and Comparative Examples3-8 to 3-17. It shows that the greater the rolling resistance index, thesmaller the rolling resistance, which is preferable.

(rolling resistance index)=(rolling resistance in Comparative Example3-1 or Comparative Example 3-8)÷(rolling resistance in each example andcomparative example)×100

(f) Static Air Pressure Drop Rate

Each manufactured tire of 195/65R15 size was mounted on a JIS standardrim 15×6JJ, and air was sealed therein at an initial air pressure of 300kPa. Then, the tire was left at room temperature for 90 days andthereafter an air pressure drop rate (%/month) was calculated.

(g) Uniformity

In conformity with the “Method for Testing Uniformity of AutomobileTire” of JASO-C607:2000, radial force variation (RFV) was measured usinga tire uniformity tester. A relative value obtained by assuming thevalue in Comparative Example 3-1 as 100 was expressed as an index. Thegreater the index, the more excellent the uniformity. Measurement wasperformed under the conditions of a rim of 8.0×17, a tire rotation speedof 60 rpm, an air pressure of 200 kPa, and a longitudinal load of 4000kN.

(Overall Judgment)

Criteria for overall judgment are as shown in Table 11.

TABLE 11 (c1) Index of (b1) Index of vulcanization unvulcanization tackadhesive strength strength with carcass with carcass layer layer (c2)Index of (b2) Index of vulcanization (f) Static air (a) Mooneyunvulcanization tack adhesive strength (e) Index of (d) Rolling pressuredrop Overall viscosity of strength between first between first andweight resistance rate Judgment Judgment Criteria first layer and secondlayers second layers saving effect index (%/month) A All of (a) to (f)satisfy 45 or less 60 or more 80 or more 110 or more 100 or more 2.5 orless conditions on the right. B Any one of (a) to (f) satisfies 46 to 5040 to 59 60 to 79 100 to 109 90 to 99 2.6 to 3.9 a correspondingcondition on the right. If a plurality of judgments are made, a judgmentwith lower evaluation is adopted. C Any one of (a) to (f) satisfies 51or more 39 or less 59 or less 99 or less 89 or less 4.0 or more acorresponding condition on the right. If a plurality of judgments aremade, a judgment with lower evaluation is adopted.

Example 4

Hereinafter, a method for manufacturing a pneumatic tire in accordancewith the present invention will be described based on examples.

<Composite Body>

The thermoplastic elastomers (SIB, SIBS, and SIS) used to manufacture acomposite body formed of a first layer and a second layer in accordancewith the present invention were prepared as described below.

[SIB]

In a 2 L reaction vessel equipped with a stirrer, 589 mL ofmethylcyclohexane (dried with molecular sieves), 613 ml of n-butylchloride (dried with molecular sieves), and 0.550 g of cumyl chloridewere charged. After cooling the reaction vessel to −70° C., 0.35 mL ofα-picoline (2-methylpyridine) and 179 mL of isobutylene were added.Further, 9.4 mL of titanium tetrachloride was added to startpolymerization, and then the solution was reacted for 2.0 hours whilebeing stirred at −70° C. Next, 59 mL of styrene was added into thereaction vessel and the reaction was continued for another 60 minutes,and then the reaction was terminated by adding a large amount ofmethanol. After removing the solvent and the like from the reactionsolution, a polymer was dissolved in toluene and washed twice withwater. This toluene solution was added to the methanol mixture, therebyprecipitating the polymer, and the resultant polymer was dried at 60° C.for 24 hours to obtain a styrene-isobutylene diblock copolymer (having astyrene component content of 15% by mass and a weight-average molecularweight of 70,000).

[SIBS]

“SIBSTAR 102 (having a Shore A hardness of 25, a styrene componentcontent of 15% by mass, and a weight-average molecular weight of100,000)” manufactured by Kaneka Corporation was used.

[SIS]

D1161JP (having a styrene component content of 15% by mass and aweight-average molecular weight of 150,000) manufactured by KratonPerformance Polymers Inc. was used.

<Method for Manufacturing Inner Liner>

The styrene-based thermoplastic elastomer such as the SIBS, SIS, SIB, orthe like described above was charged into a twin-screw extruder (screwdiameter: φ50 mm; L/D: 30; cylinder temperature: 220° C.) to obtainpellets. Thereafter, the pellets were blended with various compoundingagents in a T-die extruder (screw diameter: φ80 mm; L/D: 50; die gapwidth: 500 mm; cylinder temperature: 220° C., film gauge: 0.3 mm) tofabricate an inner liner.

<Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step described above. Pneumatic tires of examples andcomparative examples having specifications shown in Tables 12 to 17 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8. Tables12 to 17 show formulations of the inner liner and methods of moldingtires, together with evaluation results on the tires.

In the examples, displaced distance (amount) L was changed to 50 mm, 500mm, or 250 mm by setting the length of the inner liner to 1300 mm andchanging the dimension of the carcass ply, with reference to FIG. 5. Inaddition, the width (W1) of the carcass ply was set to 800 mm, and thewidth (W2) of the inner liner was set to 1300 mm.

TABLE 12 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp.ex.* ex. ex. ex. ex. ex. ex. ex. ex. ex. 4-1 4-2 4-3 4-4 4-5 4-6 4-7 4-84-9 4-10 First layer SIBS (% by mass) 100 100 100 100 100 100 100 100100 100 Tackifier A — — — — 0.05 200 — — — — Tackifier B — — — — — — — —— — Tackifier C — — — — — — — — — — Stearic acid 3 3 3 3 3 3 3 3 3 3Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Thickness of SIBS 0.25 0.25 0.25 0.25 0.25 0.25 0.030.7 0.25 0.25 layer [mm] Second Second-a layer: SIS 100 100 — 100 100100 100 100 100 100 layer Second-b layer: SIB — — 100 — — — — — — — SIBS— — — — — — — — — — Tackifier A — — — — — — — — 1 1 Tackifier B — — — —— — — — — — Tackifier C — — — — — — — — — — Stearic acid 3 3 3 3 3 3 3 33 3 Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Thickness of second-a 0.05 0.05 — 0.05 0.05 0.050.05 0.05 0.05 — layer: SIS [mm] Thickness of second-b — — 0.05 — — — —— — 0.05 layer: SIB [mm] Inner liner dimension [mm] 1300 1300 1260 7001300 1300 1300 1300 1300 1260 Carcass ply dimension [mm] 1250 1260 700600 1250 1250 1250 1250 1260 700 Displaced amount between 50 0 40 600 5050 50 50 0 40 inner liner and carcass ply in width direction [mm] TireTest Vulcanization adhesion (index) 100 99 95 94 91 106 92 95 98 95 Flexcrack growth (index) 100 95 94 92 90 75 91 93 93 94 Rolling resistancechange 100 99 97 98 89 70 99 99 96 97 rate (index) Static air pressuredrop 2.9 2.8 2.8 2.8 2.9 3.3 2.9 2.8 2.9 2.8 rate (%/month) Uniformity(index) 100 89 88 87 84 78 98 93 94 93 *Comp. ex.: Comparative example

TABLE 13 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp.ex.* ex. ex. ex. ex. ex. ex. ex. ex. ex. 4-11 4-12 4-13 4-14 4-15 4-164-17 4-18 4-19 4-20 First layer SIBS (% by mass) 100 100 100 100 100 100100 100 100 100 Tackifier A — — — — — — — 1 1 1 Tackifier B — — — — — —— — — — Tackifier C — — — — — — — — — — Stearic acid 3 3 3 3 3 3 3 3 3 3Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Thickness of SIBS 0.25 0.25 0.25 0.25 0.25 0.25 0.250.25 0.25 0.25 layer [mm] Second Second-a layer: SIS 100 100 100 100 100100 100 90 90 90 layer Second-b layer: SIB — — — — — — — — — — SIBS — —— — — — — 10 10 10 Tackifier A 1 — — — — — — — — — Tackifier B — 1 1 1 —— — — — — Tackifier C — — — — 1 1 1 1 1 1 Stearic acid 3 3 3 3 3 3 3 3 33 Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Thickness of second-a 0.05 0.05 — 0.05 0.05 — 0.050.05 — 0.05 layer: SIS [mm] Thickness of second-b — — 0.05 — — 0.05 — —0.05 — layer: SIB [mm] Inner liner dimension [mm] 700 1300 1260 700 13001260 700 1300 1260 700 Carcass ply dimension [mm] 600 1260 700 600 1260700 600 1260 700 600 Displaced amount between 600 0 40 600 0 40 600 0 40600 inner liner and carcass ply in width direction [mm] Tire TestVulcanization adhesion (index) 95 95 95 95 95 96 96 98 99 97 Flex crackgrowth (index) 94 92 95 94 94 95 95 94 95 95 Rolling resistance change95 95 97 95 95 97 95 95 97 95 rate (index) Static air pressure drop 2.72.9 2.8 2.7 2.9 2.8 2.9 2.9 2.8 2.9 rate (%/month) Uniformity (index) 9394 93 94 94 93 94 94 93 94 *Comp. ex.: Comparative example

TABLE 14 Example Example Example Example Example Example Example Example4-1 4-2 4-3 4-4 4-5 4-6 4-7 4-8 First layer SIBS (% by mass) 100 100 100100 100 100 100 100 Tackifier A — — — — — — — — Tackifier B — — — — — —— — Tackifier C — — — — — — — — Stearic acid 3 3 3 3 3 3 3 3 Zinc oxide5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 Vulcanization accelerator1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Thickness of SIBS0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 layer [mm] Second Second-alayer: SIS 90 — 20 — 100 100 100 100 layer Second-b layer: SIB — 90 — 20— — — — SIBS 10 10 80 80 — — — — Tackifier A — — — — 1 1 1 — Tackifier B— — — — — — — 1 Tackifier C — — — — — — — — Stearic acid 3 3 3 3 3 3 3 3Zinc oxide 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 Vulcanizationaccelerator 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Thickness of second-a 0.05 0.05 0.05 0.05 0.05 — 0.05 0.05 layer: SIS[mm] Thickness of second-b — — — — — 0.05 — — layer: SIB [mm] Innerliner dimension [mm] 1300 1300 1300 1300 1300 1300 1300 1300 Carcass plydimension [mm] 1250 1250 1250 1250 1250 800 800 1250 Displaced amountbetween 50 50 50 50 50 500 250 50 inner liner and carcass ply in widthdirection [mm] Tire Test Vulcanization adhesion (index) 172 172 252 255253 251 240 254 Flex crack growth (index) 130 130 150 150 151 150 149149 Rolling resistance change 105 105 106 106 107 106 105 108 rate(index) Static air pressure drop 1.7 1.7 1.5 1.5 1.9 1.8 1.9 1.9 rate(%/month) Uniformity (index) 105 104 104 104 110 108 109 109

TABLE 15 Example Example Example Example Example Example Example ExampleExample 4-9 4-10 4-11 4-12 4-13 4-14 4-15 4-16 4-17 First layer SIBS (%by mass) 100 100 100 100 100 100 100 100 100 Tackifier A — — — — — — — —— Tackifier B — — — — — — — — — Tackifier C — — — — — — — — — Stearicacid 3 3 3 3 3 3 3 3 3 Zinc oxide 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 11 1 1 1 1 1 Vulcanization accelerator 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 Thickness of SIBS 0.25 0.25 0.25 0.25 0.250.25 0.25 0.25 0.25 layer [mm] Second Second-a layer: SIS 100 100 100100 100 — 100 — 90 layer Second-b layer: SIB — — — — — 100 — 100 — SIBS— — — — — — — — 10 Tackifier A — — — — — 1 100 — 1 Tackifier B 1 1 — — —— — — — Tackifier C — — 1 1 1 — — — — Stearic acid 3 3 3 3 3 3 3 3 3Zinc oxide 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 Thickness of second-a — 0.05 0.05 — 0.05 0.05 0.05 0.050.05 layer: SIS [mm] Thickness of second-b — — — — — — — — — layer: SIB[mm] Inner liner dimension [mm] 1300 1300 1300 1300 1300 1300 1300 13001300 Carcass ply dimension [mm] 1250 1250 1250 1250 1250 1250 1250 12501250 Displaced amount between 50 50 50 50 50 50 50 50 50 inner liner andcarcass ply in width direction [mm] Tire Test Vulcanization adhesion 211233 230 221 219 153 254 255 210 (index) Flex crack growth (index) 149148 140 140 140 140 170 170 160 Rolling resistance change 108 106 103103 103 103 101 101 105 rate (index) Static air pressure drop 2 2.1 1.91.8 2 1.9 2 2 1.7 rate (%/month) Uniformity (index) 109 109 109 109 109104 110 109 104

TABLE 16 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- pleple ple ple ple ple ple ple ple ple 4-18 4-19 4-20 4-21 4-22 4-23 4-244-25 4-26 4-27 First SIBS (% by mass) 100 100 100 100 100 100 100 100100 100 layer Tackifier A — — — — — 1 1 1 1 1 Tackifier B — — — — — — —— — — Tackifier C — — — — — — — — — — Stearic acid 3 3 3 3 3 3 3 3 3 3Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 1Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Thickness of SIBS 0.25 0.25 0.25 0.25 0.25 0.25 0.250.25 0.25 0.25 layer [mm] Second Second-a layer: SIS — — — 90 20 90 20100 100 100 layer Second-b layer: SIB 90 20 20 — — — — — — — SIBS 10 8080 10 80 10 80 1 100 — Tackifier A 1 1 1 100 100 — — — — 1 Tackifier B —— — — — — — — — — Tackifier C — — — — — — — — — — Stearic acid 3 3 3 3 33 3 3 3 3 Zinc oxide 5 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 11 Vulcanization accelerator 1 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 Thickness of second-a 0.05 0.05 0.05 0.05 0.050.05 0.05 0.05 0.05 0.05 layer: SIS [mm] Thickness of second-b — — — — —— — — — — layer: SIB [mm] Inner liner dimension 1300 1300 1300 1300 13001300 1300 1300 1300 1300 [mm] Carcass ply dimension 1250 1250 1250 12501250 1250 1250 1250 1250 1250 [mm] Displaced amount between 50 50 50 5050 50 50 50 50 50 inner liner and carcass ply in width direction [mm]Tire Vulcanization adhesion 209 289 288 310 391 224 322 210 311 200 Test(index) Flex crack growth (index) 160 180 180 190 200 170 170 160 110160 Rolling resistance change 105 106 105 106 105 106 110 106 108 107rate (index) Static air pressure drop 1.7 1.5 1.5 1.7 1.5 1.7 1.5 1.81.9 1.9 rate (%/month) Uniformity (index) 105 110 109 110 109 104 104108 109 108

TABLE 17 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 4-28ple 4-29 ple 4-30 ple 4-31 ple 4-32 ple 4-33 ple 4-34 ple 4-35 ple 4-36First layer SIBS (% by mass) 100 100 100 100 100 100 100 100 100Tackifier A 1 1 1 1 100 — — — — Tackifier B — — — — — 1 100 — —Tackifier C — — — — — — — 1 100 Stearic acid 3 3 3 3 3 3 3 3 3 Zincoxide 5 5 5 5 5 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 Vulcanizationaccelerator 1 1 1 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Thickness of SIBS layer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.250.25 Second Second-a layer: SIS 100 100 100 90 90 90 90 90 90 layerSecond-b layer: SIB — — — — — — — — — SIBS — — — 10 10 10 10 10 10Tackifier A 100 — — 1 1 1 1 1 1 Tackifier B — — — — — — — — — TackifierC — 1 100 — — — — — — Stearic acid 3 3 3 3 3 3 3 3 3 Zinc oxide 5 5 5 55 5 5 5 5 Age inhibitor 1 1 1 1 1 1 1 1 1 Vulcanization accelerator 1 11 1 1 1 1 1 1 Sulfur 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Thickness ofsecond-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05Thickness of second-b layer: SIB [mm] — — — — — — — — — Inner linerdimension [mm] 1300 1300 1300 1300 1300 1300 1300 1300 1300 Carcass plydimension [mm] 1250 1250 1250 1250 1250 1250 1250 1250 1250 Displacedamount between inner liner 50 50 50 50 50 50 50 50 50 and carcass ply inwidth direction [mm] Tire Test Vulcanization adhesion (index) 300 200300 250 350 330 230 230 300 Flex crack growth (index) 116 165 116 200150 140 190 190 140 Rolling resistance change rate (index) 109 108 110110 101 101 108 108 101 Static air pressure drop rate (%/month) 1.9 2.11.7 1.7 1.7 1.7 1.7 1.7 1.9 Uniformity (index) 109 104 108 107 108 110106 107 108 (*1) tackifier A: C9 petroleum resin, ARKON P140(manufactured by Arakawa Chemical Industries Co., Ltd, and having asoftening point of 140° C. and a weight-average molecular weight Mw of900) (*2) tackifier B: terpene resin, YS Resin PX1250 (manufactured byYasuhara Chemical Co., Ltd, and having a softening point of 125° C. anda weight-average molecular weight Mw of 700) (*3) tackifier C:hydrogenated rosin ester, Super Ester A125 (manufactured by ArakawaChemical Industries Co., Ltd, and having a softening point of 125° C.and a weight-average molecular weight Mw of 700) (*4) stearic acid:“Stearic Acid Lunac S30” manufactured by Kao Corporation (*5) zinc oxide(ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & Smelting Co.,Ltd. (*6) age inhibitor: “Noclac 6C” manufactured by Ouchi ShinkoChemical Industrial Co., Ltd. (*7) vulcanization accelerator: “NoccelerDM” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (*8)sulfur: “Sulfur Powder” manufactured by Tsurumi Chemical Industry Co.,Ltd.

Comparative Examples 4-1 to 4-20

Comparative Examples 4-1 to 4-4 and Comparative Examples 4-7, 4-8 arecases where neither of the first layer and the second layer is blendedwith a tackifier, Comparative Examples 4-5, 4-6 are cases where thefirst layer is blended with a tackifier, and Comparative Examples 4-9 to4-20 are cases where the second layer is blended with a tackifier.Comparative Examples 4-18 to 4-20 are cases where the first layer isblended with a tackifier and the second layer is blended with atackifier and the SIBS.

Examples 4-1 to 4-36

Examples 4-1 to 4-22 are cases where the first layer is not blended witha tackifier and the second layer is blended with the SIBS or atackifier. Examples 4-23 to 4-36 are cases where the first layer and thesecond layer are blended with the SIBS or a tackifier.

Since the first layer or the second layer is blended with apredetermined amount of the SIBS or tackifier in Examples 4-1 to 4-36,Examples 4-1 to 4-36 are comprehensively more excellent in vulcanizationadhesive strength, flex crack growth, rolling resistance change rate,static air pressure drop rate, and uniformity, than Comparative Example4-1.

The following performance evaluation was performed on the pneumatictires manufactured as described above.

<Vulcanization Adhesive Strength>

The first layer and a carcass ply layer or the unvulcanized rubber sheetof the first layer and the second layer and a carcass ply layer werebonded together, and were vulcanized at 170° C. for 20 minutes tofabricate a sample for measuring vulcanization adhesive strength. Apeel-off strength was measured by a tensile tester as vulcanizationadhesive strength. The vulcanization adhesive strength in each exampleand comparative example was expressed as an index by the followingcalculation equation, using the value in Comparative Example 4-1 as areference value. It shows that the greater the index of thevulcanization adhesive strength, the higher the vulcanization adhesivestrength.

vulcanization adhesive strength index=(vulcanization adhesive strengthin each example and comparative example)/(vulcanization adhesivestrength in Comparative Example 4-1)×100

<Flex Crack Growth>

A flex crack growth test was performed to make an evaluation based onwhether the inner liner was broken or peeled off Each prototype tire wasmounted on a JIS standard rim 15×6JJ, and the inside of the tire wasmonitored under the conditions of a tire internal pressure of 150 KPa,which is lower than usual, a load of 600 kg, a speed of 100 km/hour, anda driving distance of 20,000 km, to measure the number of cracked/peeledportions. A relative value in each example and comparative example wascalculated using the value in Comparative Example 4-1 as a referencevalue, to express flex crack growth as an index. It shows that thegreater the value of the index, the smaller the flex crack growth.

flex crack growth index=(the number of cracked portions in ComparativeExample 4-1)/(the number of cracked portions in each example andcomparative example)×100

<Rolling Resistance>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, androlling resistance was measured while driving the tire at roomtemperature (30° C.) under the conditions of a load of 3.4 kN, an airpressure of 230 kPa, and a speed of 80 km/hour, using a rollingresistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, a rolling resistance change rate (%) ineach example and comparative example was expressed as an index, usingthe value in Comparative Example 4-1 as a reference value 100. It showsthat the greater the rolling resistance change rate, the smaller therolling resistance.

rolling resistance change rate index=(rolling resistance in ComparativeExample 4-1)/(rolling resistance in each example and comparativeexample)×100

<Static Air Pressure Drop Rate>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, and airwas sealed therein at an initial air pressure of 300 kPa. Then, the tirewas left at room temperature for 90 days and thereafter an air pressuredrop rate was calculated. The smaller the value, the less likely the airpressure is to be reduced.

<Uniformity>

In conformity with the “Method for Testing Uniformity of AutomobileTire” of JASO-C607:2000, radial force variation (RFV) was measured usinga tire uniformity tester. A relative value obtained by assuming thevalue in Comparative Example 4-1 as 100 was expressed as an index. Thegreater the index, the more excellent the uniformity. Measurement wasperformed under the conditions of a rim of 8.0×17, a tire rotation speedof 60 rpm, an air pressure of 200 kPa, and a longitudinal load of 4000kN.

Example 5

Hereinafter, a method for manufacturing a pneumatic tire in accordancewith the present invention will be described based on examples.

<Preparation of Elastomer Components>

Elastomers used for a first layer and a second layer in accordance withthe present invention were prepared as described below.

(1) Isobutylene-Based Modified Copolymer

(1-1) Component A-1: (styrene/(β-pinene)-isobutylene-(styrene/(β-pinene)Block Copolymer ((β-Pinene Content: 9.7% by Mass, Number-AverageMolecular Weight (Mn): 103,000).

A method for manufacturing component A-1 is as follows.

Air inside a container of a 2 L-separable flask was substituted bynitrogen, and 31.0 mL of n-hexane dried with molecular sieves and 294.6mL of similarly dried butyl chloride were added using a syringe. Thepolymerization container was immersed and cooled in a mixture bath ofdry ice and methanol of −70° C. Then, a liquid feed tube made of Teflon(registered trademark) was connected to a liquefaction and collectiontube made of a pressure-resistant glass with a three-way stop cockcontaining 88.9 mL (941.6 mmol) of isobutylene monomer, and theisobutylene monomer was fed into the polymerization container by meansof nitrogen pressure. Then, 0.148 g (0.6 mmol) of p-dicumylchloride and0.07 g (0.8 mmol) of α-picoline were added. Furthermore, 0.87 mL (7.9mmol) of titanium tetrachloride was added to start polymerization. Thepolymerized solution was agitated at a similar temperature for 1.5 hoursfrom the start of polymerization, and then, 1 mL of the polymerizedsolution was extracted from the polymerized solution as a sample. Then,10.4 g (99.4 mmol) of styrene monomer and 6.8 g (49.7 mmol) of β-pinenewhich had been cooled to −70° C. were uniformly agitated and added intothe polymerization container. After 45 minutes since the addition ofstyrene and β-pinene, approximately 40 mL of methanol was added toterminate the reaction. After evaporating the solvent and the like fromthe reaction solution, a polymer was dissolved in toluene and washedtwice with water. The toluene solution was added to a large amount ofmethanol to precipitate the polymer. The resultant product was vacuumdried at 60° C. for 24 hours. The molecular weight of the blockcopolymer obtained by the GPC method was measured. The number-averagemolecular weight (Mn) is 103,000, and Mw/Mn is 1.21.

(1-2) Component A-2: (styrene/(β-pinene)-isobutylene-(styrene/(β-pinene)Block Copolymer ((β-Pinene Content: 5.3% by Mass, Number-AverageMolecular Weight: 10,7000).

A method for manufacturing component A-2 is as follows.

Air inside a container of a 2 L-separable flask was substituted bynitrogen, and 31.0 mL of n-hexane dried with molecular sieves and 294.6mL of similarly dried butyl chloride were added using a syringe. Thepolymerization container was immersed and cooled in a mixture bath ofdry ice and methanol of −70° C. Then, a liquid feed tube made of Teflon(registered trademark) was connected to a liquefaction and collectiontube made of a pressure-resistant glass with a three-way stop cockcontaining 88.9 mL (941.6 mmol) of isobutylene monomer, and theisobutylene monomer was fed into the polymerization container by meansof nitrogen pressure. Then, 0.148 g (0.6 mmol) of p-dicumylchloride and0.07 g (0.8 mmol) of α-picoline were added.

Next, 0.87 mL (7.9 mmol) of titanium tetrachloride was added to startpolymerization. The polymerized solution was agitated at the sametemperature for 1.5 hours from the start of polymerization, and then, 1mL of the polymerized solution was extracted from the polymerizedsolution as a sample. Then, 10.4 g (99.4 mmol) of styrene monomer and3.6 g (26.3 mmol) of β-pinene which had been cooled to −70° C. wereuniformly agitated and added into the polymerization container. After 45minutes since the addition of styrene and β-pinene, approximately 40 mLof methanol was added to terminate the reaction. After evaporating thesolvent and the like from the reaction solution, the reaction solutionwas dissolved in toluene and washed twice with water. Further, thetoluene solution was added to a large amount of methanol to precipitatea polymer. The resultant polymer was vacuum dried at 60° C. for 24hours. The molecular weight of the block polymer obtained by the GPCmethod was measured. The number-average molecular weight (Mn) of theblock copolymer is 107,000, and Mw/Mn is 1.23.

(1-3) Component A-3: styrene-(isobutylene/(β-pinene)-styrene BlockCopolymer ((β-Pinene Content: 5.3% by Mass, Number-Average MolecularWeight: 10,9000).

A method for manufacturing component A-3 is as follows.

Air inside a polymerization container of a 2 L-separable flask wassubstituted by nitrogen, and 31.0 mL of n-hexane dried with molecularsieves and 294.6 mL of butyl chloride dried with molecular sieves wereadded using a syringe. The polymerization container was immersed andcooled in a mixture bath of dry ice and methanol of −70° C., and 3.6 g(26.3 mmol) of β-pinene was added.

Next, a liquid feed tube made of Teflon (registered trademark) wasconnected to a liquefaction and collection tube made of apressure-resistant glass with a three-way stop cock containing 88.9 mL(941.6 mmol) of isobutylene monomer, and the isobutylene monomer was fedinto the polymerization container by means of nitrogen pressure.Further, 0.148 g (0.6 mmol) of p-dicumylchloride and 0.07 g (0.8 mmol)of α-picoline were added. Next, 0.87 mL (7.9 mmol) of titaniumtetrachloride was further added to start polymerization. After 45minutes since the start of polymerization, 10.4 g (99.4 mmol) of styrenemonomer which had been cooled to −70° C. was added in the polymerizationcontainer. After 45 minutes since the addition of styrene, approximately40 mL of methanol was added to terminate the reaction. After evaporatingthe solvent and the like from the reaction solution, a polymer wasdissolved in toluene and washed twice with water. The toluene solutionwas added to a large amount of methanol to precipitate the polymer. Theresultant polymer was vacuum dried at 60° C. for 24 hours. The molecularweight of the block copolymer obtained by the GPC method was measured.The number-average molecular weight (Mn) of the block copolymer is109,000, and Mw/Mn is 1.21.

(2) SIB (Styrene-Isobutylene Block Copolymer)

In a 2 L reaction vessel equipped with a stirrer, 589 mL ofmethylcyclohexane (dried with molecular sieves), 613 ml of n-butylchloride (dried with molecular sieves), and 0.550 g of cumyl chloridewere charged. After cooling the reaction vessel to −70° C., 0.35 mL ofα-picoline (2-methylpyridine) and 179 mL of isobutylene were added.Further, 9.4 mL of titanium tetrachloride was added to startpolymerization, and then the solution was reacted for 2.0 hours whilebeing stirred at −70° C. Next, 59 mL of styrene was added into thereaction vessel and the reaction was continued for another 60 minutes,and then the reaction was terminated by adding a large amount ofmethanol. After removing the solvent and the like from the reactionsolution, a polymer was dissolved in toluene and washed twice withwater. This toluene solution was added to the methanol mixture, therebyprecipitating the polymer, and the resultant polymer was dried at 60° C.for 24 hours to obtain a styrene-isobutylene diblock copolymer (having astyrene component content of 15% by mass and a weight-average molecularweight of 70,000).

(3) SIBS (Styrene-Isobutylene-Styrene Block Copolymer)

“SIBSTAR 102T (having a Shore A hardness of 25, a styrene componentcontent of 25% by mass, and a weight-average molecular weight of100,000)” manufactured by Kaneka Corporation was used.

(4) SIS (Styrene-Isoprene-Styrene Block Copolymer)

D1161JP (having a styrene component content of 15% by mass, and aweight-average molecular weight of 150,000) manufactured by KratonPerformance Polymers Inc. was used.

(5) As the IIR, “Exxon Chlorobutyl 1066” Manufactured by Exxon MobilCorporation was used.

<Preparation of Elastomer Compositions of First Layer and Second Layer>

As shown in Tables 18 and 19, additives were blended into theabove-described elastomer components, and the elastomer compositions ofthe first and second layers were prepared.

TABLE 18 Formulations First layer formulation 5-1 5-2 5-3 5-4 5-5 5-65-7 5-8 5-9 5-10 Formulation Component A-1 100 — — 100 100 100 30 70 3050 (parts by mass) Component A-2 — 100 — — — — — — — — Component A-3 — —100 — — — — — — — SIBS — — — — — — — — — 50 IIR — — — — — — 70 30 70 —CB — — — — — — 60 60 60 — ZnO — — — 4.0 — — 4.0 4.0 4.0 — Stearic acid —— — 2.0 — — 2.0 2.0 2.0 — Age inhibitor — — — 0.2 — — 0.2 0.2 0.2 —Vulcanization — — — 2.0 — — 2.0 2.0 2.0 — accelerator Sulfur — — — 1.0 —— 1.0 1.0 1.0 — Tackifier — — — —  10 — — — 10 — Polyisobutylene — — — —— 10 — — 10 — Formulations Comparative formulations First layerformulation 5-11 5-12 5-13 5-14 5-15 5-1 5-2 5-3 5-4 FormulationComponent A-1 50 50 15 — — — — — — (parts by mass) Component A-2 — — —50 — — — — — Component A-3 — — — — 50 — — — — SIBS 50 50 15 50 50 100100 100 100 IIR — — 70 — — — — — — CB — — 60 — — — — — — ZnO — — 4.0 — —— — — 4.0 Stearic acid — — 2.0 — — — — — 2.0 Age inhibitor — — 0.2 — — —— — 0.2 Vulcanization — — 2.0 — — — — — 2.0 accelerator Sulfur — — 1.0 —— — — — 1.0 Tackifier 10 — — — — —  10 — — Polyisobutylene — 10 — — — ——  10 —

TABLE 19 Formulations Comparative formulations Second layer formulation5-16 5-17 5-18 5-19 5-20 5-21 5-22 5-23 5-24 5-5 5-6 5-7 5-8 5-10Formulation SIS 50 50 50 — 50 50 50 — 25 100 — 50 100 100 (parts by SIB— — — 50 — — — 50 — — 100 — — — mass) SIBS — — — — — — — — — — — 50 — —Component A-1 50 — — 50 50 50 50 50 25 — — — — — Component A-2 — 50 — —— — — — — — — — — — Component A-3 — — 50 — — — — — — — — — — — IIR — — —— — — — — 50 — — — — — CB — — — — — — — — 60 — — — — — ZnO — — — — 4.0 —— 4.0 4.0 — — — 4.0 — Stearic acid — — — — 2.0 — — 2.0 2.0 — — — 2.0 —Age inhibitor — — — — 0.2 — — 0.2 0.2 — — — 0.2 — Vulcanization — — — —2.0 — — 2.0 2.0 — — — 2.0 — accelerator Sulfur — — — — 1.0 — — 1.0 1.0 —— — 1.0 — Tackifier — — — — — 10 — 10 10 — — — — — Polyisobutylene — — —— — — 10 10 10 — — — —  10 (*1) IIR: “Exxon Chlorobutyl 1066”manufactured by Exxon Mobil Corporation (*2) carbon black (CB): “SEASTV” (N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3)zinc oxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining &Smelting Co., Ltd. (*4) stearic acid: “Stearic Acid Lunac S30”manufactured by Kao Corporation (*5) age inhibitor: “Noclac 6C”manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (*6)vulcanization accelerator: “Nocceler DM” manufactured by Ouchi ShinkoChemical Industrial Co., Ltd. (*7) sulfur: “Sulfur Powder” manufacturedby Tsurumi Chemical Industry Co., Ltd. (*8) tackifier: C9 petroleumresin, ARKON P140 (manufactured by Arakawa Chemical Industries Co., Ltd,and having a softening point of 140° C. and a weight-average molecularweight Mw of 900) (*9) polyisobutylene: “TETRAX 3T” (having aviscosity-average molecular weight of 30,000 and a weight-averagemolecular weight of 49,000) manufactured by Nippon Oil Corporation

<Method for Manufacturing Inner Liner>

Based on the formulations in Tables 18 and 19, additives were added tothermoplastic elastomers such as an isoprene-based modified copolymer,SIBS, SIS, and SIB, and blended with a Banbury mixer, a kneader, and atwin-screw extruder (screw diameter: φ50 mm; L/D: 30; cylindertemperature: 220° C.), thereby obtaining elastomer compositions.Thereafter, an inner liner was fabricated with a T-die extruder (screwdiameter: φ80 mm; L/D: 50; die gap width: 500 mm; cylinder temperature:220° C.). It is noted that the inner liner has a thickness of 0.3 mm(first layer: 0.25 mm, second layer: 0.05 mm)<

Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step shown in FIGS. 5 and 6. Pneumatic tires of examplesand comparative examples as indicated in detail in Tables 20 to 23 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8. Tables20 to 23 show formulations of the inner liner and methods of moldingtires, together with evaluation results on the tires. In the examples,displaced distance (amount) L was changed to 50 mm, 500 mm, or 250 mm bysetting the length of the inner liner to 1300 mm and changing thedimension of the carcass ply, with reference to FIG. 5. In addition,width W2 of the inner liner was set to 1300 mm, and width W1 of thecarcass ply was set to 800 mm.

TABLE 20 Example 5-1 Example 5-2 Example 5-3 First layer Formulation 1Formulation 1 Formulation 1 Second layer Formulation 16 Formulation 16Formulation 16 Thickness of first 0.25 0.25 0.25 layer [mm] Thickness of0.05 — 0.05 second-a layer: SIS [mm] Thickness of — 0.05 — second-blayer: SIB [mm] Inner liner dimension 1300 1300 1300 [mm] Carcass plydimension 1250 800 800 [mm] Displaced amount 50 500 250 between innerliner and carcass ply in width direction [mm] Vulcanization adhesive 110109 110 strength Flex crack growth 110 107 106 Rolling resistance 109108 108 change rate Static air pressure 2.0 2.2 2.2 drop rate (%/month)Uniformity 109 105 105

TABLE 21 Example Example Example Example Example Example Example Example5-4 5-5 5-6 5-7 5-8 5-9 5-10 5-11 First layer F.* 2 F. 3 F. 4 F. 5 F. 6F. 7 F. 8 F. 9 Second layer F. 16 F. 16 F. 16 F. 16 F. 16 F. 16 F. 16 F.16 Thickness of first layer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25Thickness of second-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 Thickness of second-b layer: SIB [mm] — — — — — — — — Inner linerdimension [mm] 1300 1300 1300 1300 1300 1300 1300 1300 Carcass plydimension [mm] 1250 1250 1250 1250 1250 1250 1250 1250 Displaced amountbetween inner liner 50 50 50 50 50 50 50 50 and carcass ply in widthdirection [mm] Vulcanization adhesive strength 114 109 116 114 119 107109 107 Flex crack growth 102 103 107 107 107 103 103 103 Rollingresistance change rate 104 104 103 103 103 103 103 103 Static airpressure drop rate (%/month) 2.2 2.2 2 2 2 2.2 2.2 2.2 Uniformity 105105 104 105 104 104 103 104 Example Example Example Example ExampleExample Example 5-12 5-13 5-14 5-15 5-16 5-17 5-18 First layer F. 10 F.11 F. 12 F. 13 F. 14 F. 15 F. 16 Second layer F. 16 F. 16 F. 16 F. 16 F.16 F. 16 F. 16 Thickness of first layer [mm] 0.25 0.25 0.25 0.25 0.250.25 0.25 Thickness of second-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.050.05 0.05 Thickness of second-b layer: SIB [mm] — — — — — — — Innerliner dimension [mm] 1300 1300 1300 1300 1300 1300 1300 Carcass plydimension [mm] 1250 1250 1250 1250 1250 1250 1250 Displaced amountbetween inner liner 50 50 50 50 50 50 50 and carcass ply in widthdirection [mm] Vulcanization adhesive strength 113 109 107 107 107 107107 Flex crack growth 104 103 103 103 103 103 103 Rolling resistancechange rate 103 103 103 103 103 103 103 Static air pressure drop rate(%/month) 2.5 2.2 2.2 2.2 2.2 2.2 2.2 Uniformity 104 104 103 104 105 105104 *F.: Formulation

TABLE 22 Example Example Example Example Example Example Example 5-195-20 5-21 5-22 5-23 5-24 5-25 First layer F.* 5 F. 6 F. 7 F. 8 F. 9 F.10 F. 11 Second-a layer F. 16 F. 16 F. 16 F. 16 F. 16 F. 16 F. 16Second-b layer — — — — — — — Thickness of first layer [mm] 0.25 0.250.25 0.25 0.25 0.25 0.25 Thickness of second-a layer: SIS [mm] 0.05 0.050.05 0.05 0.05 0.05 0.05 Thickness of second-b layer: SIB [mm] — — — — —— — Inner liner dimension [mm] 1300 1300 1300 1300 1300 1300 1300Carcass ply dimension [mm] 800 800 800 800 800 800 800 Displaced amountbetween inner liner 500 500 500 500 500 500 500 and carcass ply in widthdirection [mm] Vulcanization adhesive strength 117 115 117 117 115 117117 Flex crack growth 107 107 107 107 108 106 107 Rolling resistancechange rate 104 104 104 103 105 103 104 Static air pressure drop rate(%/month) 1.8 1.8 1.8 1.8 1.8 1.8 1.9 Uniformity 104 104 105 105 104 104105 Example Example Example Example Example Example Example 5-26 5-275-28 5-29 5-30 5-31 5-32 First layer F. 12 F. 13 F. 14 F. 15 F. 1 F. 1F. 1 Second-a layer F. 16 F. 16 F. 16 F. 16 F. 22 — F. 24 Second-b layer— — — — — F. 23 — Thickness of first layer [mm] 0.25 0.25 0.25 0.25 0.250.25 0.25 Thickness of second-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05— 0.05 Thickness of second-b layer: SIB [mm] — — — — — 0.05 — Innerliner dimension [mm] 1300 1300 1300 1300 1300 1300 1300 Carcass plydimension [mm] 800 800 800 800 1250 1250 1250 Displaced amount betweeninner liner 500 500 500 500 50 50 50 and carcass ply in width direction[mm] Vulcanization adhesive strength 117 117 122 120 119 127 132 Flexcrack growth 108 108 112 110 111 110 111 Rolling resistance change rate103 105 106 106 106 107 106 Static air pressure drop rate (%/month) 21.9 1.9 1.9 1.9 1.9 1.8 Uniformity 105 105 105 104 105 105 106 *F.:Formulation

TABLE 23 Comp. Comp. Comp. Comp. Comp. Comp. Comp. ex.* ex. ex. ex. ex.ex. ex. 5-1 5-2 5-3 5-4 5-5 5-6 5-7 First layer Comp. Comp. F.** 1 Comp.Comp. F.*** 1 F. 1 F. 1 F. 1 Second-a layer Comp. Comp. F. 16 — Comp. F.5 F. 5 F. 5 Second-b layer — — — Comp. Comp. F. 6 F. 6 Thickness offirst layer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thickness ofsecond-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 — 0.05 Thickness ofsecond-b layer: SIB [mm] — — — — — 0.05 0.05 Inner liner dimension [mm]1300 1300 1300 1300 1300 1300 1300 Carcass ply dimension [mm] 1250 8001300 1260 700 1250 1250 Displaced amount between inner liner and 50 5000 40 600 50 50 carcass ply in width direction [mm] Vulcanizationadhesive strength 100 100 97 97 95 101 100 Flex crack growth 100 98 9695 91 102 101 Rolling resistance change rate 100 97 95 93 93 101 99Static air pressure drop rate (%/month) 3.8 3.2 3.8 3.8 3.9 2.6 2.7Uniformity 100 98 97 95 95 95 96 Comp. Comp. Comp. Comp. Comp. Comp.Comp. ex. ex. ex. ex. ex. ex. ex. 5-8 5-9 5-10 5-11 5-12 5-13 5-14 Firstlayer Comp. Comp. Comp. Comp. Comp. Comp. F. 1 F. 3 F. 4 F. 1 F. 1 F. 1F. 1 Second-a layer Comp. Comp. Comp. Comp. Comp. Comp. F. 24 F. 5 F. 5F. 7 F. 8 F. 9 F. 10 Second-b layer — — — — — — — Thickness of firstlayer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thickness of second-alayer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Thickness of second-blayer: SIB [mm] — — — — — — — Inner liner dimension [mm] 1300 1300 13001300 1300 1300 1300 Carcass ply dimension [mm] 1250 1250 1250 1250 12501250 1250 Displaced amount between inner liner and 50 50 50 50 50 50 50carcass ply in width direction [mm] Vulcanization adhesive strength 100100 97 100 100 100 112 Flex crack growth 99 101 101 99 98 100 102Rolling resistance change rate 101 100 100 100 100 99 101 Static airpressure drop rate (%/month) 2.7 2.8 2.8 2.8 2.9 3.0 2.7 Uniformity 9696 96 96 96 96 96 *Comp. ex.: Comparative example **F.: formulation***Comp. F.: Comparative formulation

Examples 5-1 to 5-3

In Table 20, Examples 5-1 to 5-3 are cases where only anisobutylene-based modified copolymer (component A-1) was used as anelastomer component for the first layer, and the SIS and anisobutylene-based modified copolymer (component A-1) were used for thesecond layer.

Examples 5-4 to 5-18

In Table 21, Examples 5-4 to 5-18 are cases where formulationscontaining an isobutylene-based modified copolymer as an elastomercomponent (formulations 5-2 to 5-16) were used for the first layer, anda formulation having the SIS and an isobutylene-based modified copolymer(component A-1) mixed therein (formulation 5-16) was used for the secondlayer.

Examples 5-19 to 5-32

In Table 22, Examples 5-19 to 5-29 are cases where the formulationscontaining an isobutylene-based modified copolymer as an elastomercomponent (formulations 5 to 15) were used for the first layer, and theformulation having the SIS and an isobutylene-based modified copolymer(component A-1) mixed therein (formulation 16) was used for the secondlayer.

Example 5-30 is a case where a formulation made of an isobutylene-basedmodified copolymer (component A-1) (a formulation 1) was used for thefirst layer, and a formulation having the SIS and an isobutylene-basedmodified copolymer (component A-1) mixed therein (a formulation 22) wasused for the second layer.

Example 5-31 is a case where the formulation made of anisobutylene-based modified copolymer (component A-1) (formulation 1) wasused for the first layer, and a formulation having the SIB and anisobutylene-based modified copolymer (component A-1) mixed therein (aformulation 23) was used for the second layer.

Example 5-32 is a case where the formulation made of anisobutylene-based modified copolymer (component A-1) (formulation 1) wasused for the first layer, and a formulation having the SIS, anisobutylene-based modified copolymer (component A-1), and the IIR mixedtherein (a formulation 24) was used for the second layer.

It is recognized that the examples of the present invention arecomprehensively more excellent in vulcanization adhesive strength, flexcrack growth, rolling resistance index, static air pressure drop rate,and uniformity, than Comparative Example 1 described later.

Comparative Examples 5-1 to 5-14

In Table 23, Comparative Examples 5-1, 5-2, 5-6, 5-7, and 5-10 to 5-13are cases where the SIBS (comparative formation 1) was used for thefirst layer, and the SIS or the SIB was used for the second layer.

Comparative Examples 5-3 to 5-5 are cases where an isobutylene-basedmodified copolymer (component A-1) was used for the first layer, and theSIS and an isobutylene-based modified copolymer (component A-1)(formation 16) were used for the second layer. However, the displaceddistance (amount) is outside the scope of the present invention.

Comparative Example 5-14 is a case where an isobutylene-based modifiedcopolymer (component A-1) (formulation 1) was used for the first layer,and a mixture of the SIS, an isobutylene-based modified copolymer(component A-1), and the IIR (formulation 24) was used for the secondlayer.

<Performance Test>

Performance evaluation was performed on the pneumatic tires manufacturedas described above, in the following manner.

<Vulcanization Adhesive Strength>

A carcass ply was bonded to a composite layer of the first layer and thesecond layer, and vulcanized at 170° C. for 20 minutes to fabricate asample for measuring vulcanization adhesive strength. A peel-offstrength was measured by a tensile tester as vulcanization adhesivestrength. The vulcanization adhesive strength in each example andcomparative example was expressed as an index by the followingcalculation equation, using the value in Comparative Example 5-1 as areference value. It shows that the greater the index of thevulcanization adhesive strength, the higher the vulcanization adhesivestrength.

vulcanization adhesive strength index=(vulcanization adhesive strengthin each example and comparative example)/(vulcanization adhesivestrength in Comparative Example 5-1)×100

<Flex Crack Growth>

A durability driving test was performed to make an evaluation based onwhether the inner liner was broken or peeled off. Each prototype tirewas mounted on a JIS standard rim 15×6JJ, and the inside of the tire wasmonitored under the conditions of a tire internal pressure of 150 KPa,which is lower than usual, a load of 600 kg, a speed of 100 km/hour, anda driving distance of 20,000 km, to measure the number of cracked/peeledportions. Flex crack growth in each example and comparative example wasexpressed as an index, using the value in Comparative Example 5-1 as areference value. It shows that the greater the value of the index, thesmaller the flex crack growth.

flex crack growth index=(the number of cracked portions in ComparativeExample 5-1)/(the number of cracked portions in each example andcomparative example)×100

<Rolling Resistance>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, androlling resistance was measured while driving the tire at roomtemperature (30° C.) under the conditions of a load of 3.4 kN, an airpressure of 230 kPa, and a speed of 80 km/hour, using a rollingresistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, a rolling resistance change rate (%) ineach example and comparative example was expressed as an index, usingthe value in Comparative Example 5-1 as a reference value 100. It showsthat the greater the rolling resistance change rate, the smaller therolling resistance.

rolling resistance index=(rolling resistance in Comparative Example5-1)/(rolling resistance in each example and comparative example)×100

<Static Air Pressure Drop Rate Test>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, and airwas sealed therein at an initial air pressure of 300 kPa. Then, the tirewas left at room temperature for 90 days and thereafter an air pressuredrop rate was calculated. The smaller the value, the less likely the airpressure is to be reduced, which is preferable.

<Uniformity>

In conformity with the “Method for Testing Tire Uniformity of AutomobileTire” of JASO-C607:2000, RFV was measured using a tire uniformitytester, and evaluated based on an index obtained by assuming the valuein Comparative Example 1 as 100. The greater the value, the moreexcellent the uniformity. Measurement was performed under the conditionsof a rim of 8.0×17, a tire rotation speed of 60 rpm, an air pressure of200 kPa, and a longitudinal load of 4000 kN.

Example 6

Hereinafter, a method for manufacturing a pneumatic tire in accordancewith the present invention will be described based on examples.

<Composite Layer for Inner Liner>

As thermoplastic elastomer components used to manufacture a polymerlaminate made of a first layer and a second layer in accordance with thepresent invention, an SIB, an SIS, an SIBS, and an SIBS modifiedcopolymer were prepared as described below.

[SIB]

In a 2 L reaction vessel equipped with a stirrer, 589 mL ofmethylcyclohexane (dried with molecular sieves), 613 ml of n-butylchloride (dried with molecular sieves), and 0.550 g of cumyl chloridewere charged. After cooling the reaction vessel to −70° C., 0.35 mL ofα-picoline (2-methylpyridine) and 179 mL of isobutylene were added.Further, 9.4 mL of titanium tetrachloride was added to startpolymerization, and then the solution was reacted for 2.0 hours whilebeing stirred at −70° C. Next, 59 mL of styrene was added into thereaction vessel and the reaction was continued for another 60 minutes,and then the reaction was terminated by adding a large amount ofmethanol. After removing the solvent and the like from the reactionsolution, a polymer was dissolved in toluene and washed twice withwater. This toluene solution was added to the methanol mixture, therebyprecipitating the polymer, and the resultant polymer was dried at 60° C.for 24 hours to obtain a styrene-isobutylene diblock copolymer (having astyrene component content of 15% by mass and a weight-average molecularweight of 70,000).

[SIS]

D1161JP (having a styrene component content of 15% by mass and aweight-average molecular weight of 150,000) manufactured by KratonPerformance Polymers Inc. was used.

[SIBS]

“SIBSTAR 102T (having a Shore A hardness of 25, a styrene componentcontent of 15% by mass, and a weight-average molecular weight of100,000)” manufactured by Kaneka Corporation was used.

[Manufacturing of SIBS Modified Copolymer]

Into a 2-liter separable flask, 75 g of a styrene-isobutylene blockcopolymer (styrene content: 30% by mass, the number of moles of thestyrene unit: 0.216 mol) was charged, and the inside of the containerwas substituted by nitrogen. Using a syringe, 1200 mL of n-hexane driedwith molecular sieves and 1800 ml of n-butyl chloride dried withmolecular sieves were added.

Next, 30 g (0.291 mol) of methacrylic acid chloride was added using asyringe. Then, 39.4 g (0.295 mol) of aluminum trichloride was addedwhile stirring the solution to start a reaction. After the reaction for30 minutes, about 1000 ml of water was added to the reaction solution,which was stirred vigorously to terminate the reaction. The reactionsolution was washed with a large amount of water several times, andfurther slowly dropped into a large amount of a methanol-acetone mixedsolvent (1:1) to precipitate a reaction product. Then, the reactionproduct was vacuum dried at 60° C. for 24 hours to obtain an SIBSmodified copolymer (weight-average molecular weight: 150,000, styrenecontent: 20% by mass, acid chloride: 1.0% by weight).

TABLE 24 Formulations Comparative formulations First layer formulation6-1 6-2 6-3 64 6-5 6-6 6-7 6-8 6-9 6-10 6-11 6-1 6-2 6-3 64 FormulationSIBS modified 100 100 30 70 90 10 90 10 15 35 35 — — — — (parts bycopolymer mass) SIBS — — — — 10 90 10 90 15 35 35 100 100 100 100 IIR —— 70 30 — — — — 70 30 30 — — — — CB — — 60 60 — — — — 60 30 30 — — — —ZnO — 4.0 4.0 4.0 — — 4.0 4.0 4.0 4.0 4.0 — — — 4.0 Stearic acid — 2.02.0 2.0 — — 2.0 2.0 2.0 2.0 2.0 — — — 2.0 Age inhibitor — 0.2 0.2 0.2 —— 0.2 0.2 0.2 0.2 0.2 — — — 0.2 Vulcanization — 2.0 2.0 2.0 — — 2.0 2.02.0 2.0 2.0 — — — 2.0 accelerator Sulfur — 1.0 1.0 1.0 — — 1.0 1.0 1.01.0 1.0 — — — 1.0 Tackifier — — — — — — — — — — 10 —  10 — —Polyisobutylene — — — — — — — — — — 10 — —  10 —

TABLE 25 Formulations Comparative formulations Second layer formulation6-2A 6-2B 6-2C 6-2D 6-2E 6-2F 6-2G 6-5 6-6 6-7 6-8 6-9 6-10 FormulationSIS 20 20 15 10 10 — — 100 — 50 100 100 100 (parts by SIB — — — — — 1010 — 100 — — — — mass) SIBS — — — — — 10 10 — — 50 — — — SIBS modifiedcopolymer 80 80 15 80 80 10 10 — — — — — — IIR — — 70 — — 70 70 — — — —— — CB — — 6.0 — — 60 60 — — — — — — ZnO — 4.0 4.0 — 4.0 4.0 4.0 — — —4.0 — — Stearic acid — 2.0 2.0 — 2.0 2.0 2.0 — — — 2.0 — — Age inhibitor— 0.2 0.2 — 0.2 0.2 0.2 — — — 0.2 — — Vulcanization accelerator — 2.02.0 — 2.0 2.0 2.0 — — — 2.0 — — Sulfur — 1.0 1.0 — 1.0 1.0 1.0 — — — 1.0— — Tackifier — — — — — — 10 — — — —  10 — Polyisobutylene — — — — — —10 — — — — —  10 (*1) IIR: “Exxon Chlorobutyl 1066” manufactured byExxon Mobil Corporation (*2) carbon black (CB): “SEAST V” (N660, N₂SA:27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zinc oxide (ZnO):“Zinc White No. 1” manufactured by Mitsui Mining & Smelting Co., Ltd.(*4) stearic acid: “Stearic Acid Lunac S30” manufactured by KaoCorporation (*5) age inhibitor: “Noclac 6C” manufactured by Ouchi ShinkoChemical Industrial Co., Ltd. (*6) vulcanization accelerator: “NoccelerDM” manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (*7)sulfur: “Sulfur Powder” manufactured by Tsurumi Chemical Industry Co.,Ltd. (*8) tackifier: C9 petroleum resin, ARKON P140 (manufactured byArakawa Chemical Industries Co., Ltd, and having a softening point of140° C. and a weight-average molecular weight Mw of 900) (*9)polyisobutylene: “TETRAX 3T” (having a viscosity-average molecularweight of 30,000 and a weight-average molecular weight of 49,000)manufactured by Nippon Oil Corporation

<Method for Manufacturing Inner Liner>

Based on the formulations and comparative formulations in Tables 24 and25, elastomer compositions such as the SIBS modified copolymer, theSIBS, the SIS, and the SIB were formed into pellets using a twin-screwextruder (screw diameter: φ50 mm; L/D: 30; cylinder temperature: 220°C.). Thereafter, an inner liner was fabricated using a T-die extruder(screw diameter: φ80 mm; L/D: 50; die gap width: 500 mm; cylindertemperature: 220° C.; film gauge for the first layer: 0.25 mm; filmgauge for the second layer: 0.05 mm)

<Unvulcanized Rubber Sheet>

In the present invention, a carcass ply was used as an unvulcanizedrubber sheet, and its topping rubber had a formulation described below.

<Formulation A of Topping Rubber>

natural rubber (*1) 100 parts by mass carbon black (*2) 50 parts by masszinc white (*3) 3 parts by mass age inhibitor (*4) 0.2 parts by masssulfur (*5) 1 part by mass vulcanization accelerator (*6) 1 part by massvulcanization assistant (*7) 1 part by mass (*1) TSR20 (*2) “Seast V”(N660, N₂SA: 27 m²/g) manufactured by Tokai Carbon Co., Ltd. (*3) zincoxide (ZnO): “Zinc White No. 1” manufactured by Mitsui Mining & SmeltingCo., Ltd. (*4) “Noclac 6C” manufactured by Ouchi Shinko ChemicalIndustrial Co., Ltd. (*5) “Sulfur Powder” manufactured by TsurumiChemical Industry Co., Ltd. (*6) “Nocceler DM” manufactured by OuchiShinko Chemical Industrial Co., Ltd. (*7) stearic acid: “Stearic AcidLunac S30” manufactured by Kao Corporation

<Manufacturing of Pneumatic Tire>

Manufacturing of a pneumatic tire in accordance with the presentinvention was performed based on the assembly step, the cutting step,and the joining step described above. Pneumatic tires of examples andcomparative examples as indicated in detail in Tables 26 to 29 weremanufactured. A green tire was subjected to press molding at 170° C. for20 minutes for vulcanization, the vulcanized tire was cooled at 100° C.for 3 minutes without being taken out of a vulcanization mold, andthereafter taken out from the vulcanized tire to manufacture a pneumatictire of 195/65R15 size having a basic structure shown in FIG. 8. Tables26 to 29 show formulations of the inner liner and methods of moldingtires, together with evaluation results on the tires. In the examples,displaced distance (amount) L was changed to 50 mm, 500 mm, or 250 mm bysetting the length of the inner liner to 1300 mm and changing thedimension of the carcass ply, with reference to FIG. 5. In addition, thewidth (W1) of the carcass ply was set to 800 mm, and the width (W2) ofthe inner liner was set to 1300 mm.

TABLE 26 Example 6-1 Example 6-2 Example 6-3 First layer Formulation 6-1Formulation 6-1 Formulation 6-1 Second layer Formulation 6-2AFormulation 6-2A Formulation 6-2A Thickness of first layer [mm] 0.250.25 0.25 Thickness of second-a layer: SIS [mm] 0.05 0.05 0.05 Thicknessof second-b layer: SIB [mm] — — — Inner liner dimension [mm] 1300 13001300 Carcass ply dimension [mm] 1250 800 800 Displaced amount betweeninner liner and carcass ply in 50 500 250 width direction [mm]Vulcanization adhesive strength 108 107 107 Flex crack growth 103 102103 Rolling resistance change rate 104 102 103 Static air pressure droprate (%/month) 2.1 2.3 2.2 Uniformity 107 108 108

TABLE 27 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- pleple ple ple ple ple ple ple ple ple 6-4 6-5 6-6 6-7 6-8 6-9 6-10 6-116-12 6-13 First layer F.* 6-2 F. 6-3 F. 6-4 F. 6-5 F. 6-6 F. 6-7 F. 6-8F. 6-9 F. 6-10 F. 6-11 Second layer F. 6-2A F. 6-2A F. 6-2A F. 6-2A F.6-2A F. 6-2A F. 6-2A F. 6-2A F. 6-2A F. 6-2A Thickness of first layer[mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thickness ofsecond-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 Thickness of second-b layer: SIB [mm] — — — — — — — — — — Innerliner dimension [mm] 1300 1300 1300 1300 1300 1300 1300 1300 1300 1300Carcass ply dimension [mm] 1250 1250 1250 1250 1250 1250 1250 1250 12501250 Displaced amount between inner liner and 50 50 50 50 50 50 50 50 5050 carcass ply in width direction [mm] Vulcanization adhesive strength108 106 107 107 106 108 106 107 116 118 Flex crack growth 102 103 102102 102 102 103 102 103 104 Rolling resistance change rate 103 101 102102 102 103 101 102 103 103 Static air pressure drop rate (%/month) 2.12.2 2.2 2.1 2.1 2.1 2.2 2.2 2.2 2.2 Uniformity 108 107 108 108 108 110105 106 115 115 *F.: Formulation

TABLE 28 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- ple ple ple ple ple ple ple ple ple ple ple 6-14 6-15 6-16 6-176-18 6-19 6-20 6-21 6-22 6-23 6-24 First layer F.* 6-1 F. 6-1 F. 6-1 F.6-1 F. 6-1 F. 6-2 F. 6-3 F. 6-5 F. 6-7 F. 6-9 F. 6-1 Second-a layer F.6-2A F. 6-2B F. 6-2C F. 6-2D F. 6-2D F. 6-2A F. 6-2A F. 6-2A F. 6-2A F.6-2A F. 6-2G Second-b layer — — — — F. 6-2F — — — — — — Thickness offirst layer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25Thickness of second-a layer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 0.05 0.05 0.05 Thickness of second-b layer: SIB [mm] — — — — — — —— — — — Inner liner dimension [mm] 1300 1300 1300 1300 1300 1300 13001300 1300 1300 1300 Carcass ply dimension [mm] 1250 1250 1250 1250 12501250 1250 1250 1250 1250 1250 Displaced amount between inner liner 50 5050 50 50 50 50 50 50 50 50 and carcass ply in width direction [mm]Vulcanization adhesive strength 116 117 115 116 116 116 116 116 116 116118 Flex crack growth 106 107 105 106 106 106 106 106 107 107 107Rolling resistance change rate 103 103 103 103 102 103 103 103 103 103103 Static air pressure drop rate (%/month) 1.9 1.9 2 1.9 1.9 1.9 2 1.91.9 2 1.9 Uniformity 116 116 115 115 115 115 116 116 117 117 117 *F.:Formulation

TABLE 29 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp.Comp. ex.* ex. ex. ex. ex. ex. ex. ex. ex. ex. ex. 6-1 6-2 6-3 6-4 6-56-6 6-7 6-8 6-9 6-10 6-11 First layer Comp. Comp. Comp. Comp. Comp.Comp. Comp. Comp. Comp. Comp. Comp. F.** 6-1 F. 6-1 F. 6-1 F. 6-1 F. 6-2F. 6-3 F. 6-4 F. 6-1 F. 6-1 F. 6-1 F. 6-1 Second-a layer Comp. Comp. —Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. F. 6-5 F. 6-5 F. 6-5 F.6-5 F. 6-5 F. 6-5 F. 6-7 F. 6-8 F. 6-9 F. 6-10 Second-b layer — — Comp.Comp. — — — — — — — F. 6-6 F. 6-6 Thickness of first layer [mm] 0.250.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thickness of second-alayer: SIS [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05Thickness of second-b layer: SIB [mm] — — — — — — — — — — — Inner linerdimension [mm] 1300 1300 1300 1300 1300 1300 1300 1300 1300 1300 1300Carcass ply dimension [mm] 1250 800 1250 1250 1250 1250 1250 1250 12501250 1250 Displaced amount between inner liner 50 500 50 50 50 50 50 5050 50 50 and carcass ply in width direction [mm] Vulcanization adhesivestrength 100 100 101 100 100 100 100 97 100 100 100 Flex crack growth100 98 102 101 99 99 101 101 99 98 100 Rolling resistance change rate100 97 101 99 101 101 100 100 100 100 99 Static air pressure drop rate(%/month) 3.8 3.2 2.6 2.7 2.7 2.7 2.8 2.8 2.8 2.9 3.0 Uniformity 100 9895 96 96 96 96 96 96 96 96 *Comp. ex.: Comparative example **Comp. F.:Comparative formulation

<Performance Test>

The following performance evaluation was performed on the pneumatictires manufactured as described above.

<Vulcanization Adhesive Strength>

The inner liner and the unvulcanized sheet were bonded together suchthat the second layer of the inner liner was brought into contact withthe unvulcanized sheet, and vulcanized at 170° C. for 20 minutes tofabricate a sample for measuring vulcanization adhesive strength. Apeel-off strength was measured by a tensile tester as vulcanizationadhesive strength. The vulcanization adhesive strength in each exampleand comparative example was expressed as an index by the followingcalculation equation, using the value in Comparative Example 6-1 as areference value. It shows that the greater the index of thevulcanization adhesive strength, the higher the vulcanization adhesivestrength.

vulcanization adhesive strength index=(vulcanization adhesive strengthin each example and comparative example)/(vulcanization adhesivestrength in Comparative Example 6-1)×100

<Flex Crack Growth>

A durability driving test was performed to make an evaluation based onwhether the inner liner was broken or peeled off. Each prototype tirewas mounted on a JIS standard rim 15×6JJ, and the inside of the tire wasmonitored under the conditions of a tire internal pressure of 150 KPa,which is lower than usual, a load of 600 kg, a speed of 100 km/hour, anda driving distance of 20,000 km, to measure the number of cracked/peeledportions. Flex crack growth in each example and comparative example wasexpressed as an index, using the value in Comparative Example 6-1 as areference value. It shows that the greater the index, the smaller theflex crack growth.

flex crack growth index=(the number of cracked portions in ComparativeExample 6-1)/(the number of cracked portions in each example andcomparative example)×100

<Rolling Resistance>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, androlling resistance was measured while driving the tire at roomtemperature (30° C.) under the conditions of a load of 3.4 kN, an airpressure of 230 kPa, and a speed of 80 km/hour, using a rollingresistance tester manufactured by KOBE STEEL, LTD. Based on thefollowing calculation equation, a rolling resistance change rate (%) ineach example and comparative example was expressed as an index, usingthe value in Comparative Example 6-1 as a reference value 100. It showsthat the greater the rolling resistance change rate, the smaller therolling resistance.

rolling resistance index=(rolling resistance in Comparative Example6-1)/(rolling resistance in each example and comparative example)×100

<Static Air Pressure Drop Rate Test>

Each prototype tire was mounted on a JIS standard rim 15×6JJ, and airwas sealed therein at an initial air pressure of 300 kPa. Then, the tirewas left at room temperature for 90 days and thereafter an air pressuredrop rate was calculated. The smaller the value, the less likely the airpressure is to be reduced, which is preferable.

<Uniformity>

In conformity with the “Method for Testing Uniformity of AutomobileTire” of JASO-C607:2000, radial force variation (RFV) was measured usinga tire uniformity tester. A relative value obtained by assuming thevalue in Comparative Example 6-1 as 100 was expressed as an index. Thegreater the index, the more excellent the uniformity. Measurement wasperformed under the conditions of a rim of 8.0×17, a tire rotation speedof 60 rpm, an air pressure of 200 kPa, and a longitudinal load of 4000kN.

Examples 6-1 to 6-24

Tables 26 to 28 show test results of Examples 6-1 to 6-24. Here,Examples 6-1 to 6-3 are cases where a formulation 6-1 was used for thefirst layer, a formulation 6-2A was used for the second layer, and thedisplaced amount was changed. Examples 6-4 to 6-13 are cases whereformulations 6-2 to 6-11 were used for the first layer, formulation 6-2Awas used for the second layer, and the displaced amount was set constantto 50 mm.

Examples 6-14 to 6-17 are cases where formulation 1 was used for thefirst layer, formulations 2A to 2D were used for the second layer, andthe displaced amount was set constant to 50 mm. Example 6-18 is a casewhere formulation 1 was used for the first layer, a plurality of layershaving formulations 2D and 2F were used for the second layer, and thedisplaced amount was set to 50 mm.

Examples 6-19 to 6-23 are cases where formulations 2 to 9 were used forthe first layer, formulation 2A was used for the second layer, and thedisplaced amount was set constant to 50 mm. Example 6-24 is a case whereformulation 1 was used for the first layer, a formulation 2G was usedfor the second layer, and the displaced amount was set to 50 mm.

It is recognized that the examples of the present invention arecomprehensively more excellent in vulcanization adhesive strength, flexcrack growth, rolling resistance, static air pressure drop rate, anduniformity, than Comparative Example 6-1 described later.

Comparative Examples 6-1 to 6-11

Table 29 shows test results of Comparative Examples 6-1 to 6-11. Here,Comparative Examples 6-1, 6-2 are cases where a comparative formulation1 was used for the first layer, a comparative formulation 5 was used forthe second layer, and the displaced amount was changed to 50 mm or 500mm.

Comparative Examples 6-3 and 6-8 to 6-11 are cases where comparativeformulation 6-1 was used for the first layer, comparative formulation6-6 to 6-10 were used for the second layer, and the displaced amount wasset constant to 50 mm.

Comparative Example 6-4 is a case where comparative formulation 1 wasused for the first layer, a plurality of layers having comparativeformulations 5 and 6 were used for the second layer, and the displacedamount was set to 50 mm.

Examples 6-25 to 6-36: Blended with Ultraviolet Absorber/Antioxidant>

In Examples 6-25 to 6-36, pneumatic tires were manufactured as inExamples 6-1 to 6-24 described above, using the first layer formulationsshown in Table 30 and the second layer formulations shown in Table 31.Table 32 shows test results thereof.

TABLE 30 Comparative formulations Example formulations First layerformulation 1X 2X 3X 4X 5X 6X 1X 2X 3X 4X 5X 6X 7X 8X Formulation SIBS100 100 100 — 50 50 — — — — — — 50 50 (parts by SIBS modified — — — 10050 50 100 100 100 100 100 100 50 50 mass) copolymer Tackifier — — — — —— — — — — — — 10 10 Polyisobutylene — — — — — — — — — — — — 10 10Antioxidant 0.4 — 0.2 0.2 0.2 45 0.5  40 — — 0.5 0.5 0.5 20 Ultraviolet— 0.4 0.2 0.2 0.2 45 — — 0.5  40 0.5 0.5 0.5 20 absorber

TABLE 31 Comparative formulations Example formulations Second layerformulation 7X 8X 9X 10X 11X 12X 13X 9X 10X 11X 12X 13X 14X 15X 16X 17XFormulation SIS 100 100 100 — 50 50 35 — — — — — — 50 50 35 (parts bySIB — — — 100 — — — 100 100 100 100 100 100 — — — mass) SIBS — — — — 5050 35 — — — — — — 50 50 35 SIBS modified — — — — — — 30 — — — — — — — —30 copolymer Tackifier — — — — — — — — — — — — — — 10 10 Polyisobutylene— — — — — — — — — — — — — — 10 10 Antioxidant 0.4 — 0.2 0.2 0.2 45 450.5  40 — — 0.5 0.5 0.5 20 20 Ultraviolet — 0.4 0.2 0.2 0.2 45 45 — —0.5  40 0.5 0.5 0.5 20 20 absorber

TABLE 32 Examples Laminated structure 6-25 6-26 6-27 6-28 6-29 6-30 6-31Laminated First layer Ex. F.* 5X Ex. F. 5X Ex. F. 5X Ex. F. 5X Ex. F. 1XEx. F. 2X Ex. F. 3X structure Second layer Ex. F. 16X Ex. F. 16X Ex. F.16X Ex. F. 17X Ex. F. 13X Ex. F. 13X Ex. F. 13X Thickness of first layer[mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thickness of second layer [mm]0.05 0.05 0.05 0.05 0.05 0.05 0.05 Inner liner dimension length [mm]1300 1300 1300 1300 1300 1300 1300 Ply dimension length [mm] 1250 800800 1250 800 800 800 Displaced amount between inner 50 500 250 50 250250 250 liner and carcass ply in width direction [mm] Evaluation Weatherresistance index 119 120 125 123 118 119 118 Flex crack growth index 118120 120 121 119 119 120 Elasticity change index 121 119 123 122 120 120120 Durability driving index 121 121 123 126 121 120 121 Uniformity 118118 126 120 119 118 119 Examples Laminated structure 6-32 6-33 6-34 6-356-36 Laminated First layer Ex. F. 4X Ex. F. 5X Ex. F. 6X Ex. F. 7X Ex.F. 8X structure Second layer Ex. F. 13X Ex. F. 13X Ex. F. 13X Ex. F. 13XEx. F. 13X Thickness of first layer [mm] 0.25 0.25 0.25 0.25 0.25Thickness of second layer [mm] 0.05 0.05 0.05 0.05 0.05 Inner linerdimension length [mm] 1300 1300 1300 1300 1300 Ply dimension length [mm]800 800 800 800 800 Displaced amount between inner 250 250 250 250 250liner and carcass ply in width direction [mm] Evaluation Weatherresistance index 120 120 121 122 120 Flex crack growth index 120 119 120119 120 Elasticity change index 120 120 120 119 120 Durability drivingindex 120 120 121 120 121 Uniformity 120 119 119 118 119 *Ex. F: Exampleformulation

The ultraviolet absorber and the antioxidant used in Tables 30 and 31are described below. Other components are the same as those used inExamples 6-1 to 6-24.

(*1) As the ultraviolet absorber, ADK STAB LA-36(2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazol),which is a benzotriazol-based ultraviolet absorber manufactured by ADEKACorporation, was used. The ultraviolet absorber has a molecular weightof 315.8, a melting point of 138 to 141° C., and a maximum absorptionwavelength of 353 nm.

(*2) As the antioxidant, “IRGANOX 1010” (pentaerythrityltetrakis(3-3,5-di-t-butyl-4-hydroxyphenyl) propionate) was used as ahindered phenolic antioxidant manufactured by BASF. The antioxidant hasa molecular weight of 111.7, a melting point of 110 to 125° C., and aspecific gravity of 1.15.

Comparative Examples 6-12 to 6-20

In Comparative Examples 6-12 to 6-20, pneumatic tires were manufacturedas in Comparative Examples 6-1 to 6-11 described above, using the firstlayer formulations shown in Table 30 and the second layer formulationsshown in Table 31. Table 33 shows test results thereof.

TABLE 33 Comparative examples Laminated structure 6-12 6-13 6-14 6-156-16 6-17 6-18 6-19 6-20 Laminated First layer Comp. Comp. Comp. Comp.Comp. Comp. Comp. Comp. Comp. structure F.* 1X F. 2X F. 3X F. 4X F. 3XF. 3X F. 1X F. 1X F. 1X Second layer Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex.F.**9X F..9X F. 9X F. 9X F. 11X F. 12X F. 9X F. 9X F. 9X Thickness offirst layer [mm] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Thicknessof second layer [mm] 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Innerliner dimension length [mm] 1300 1300 1300 1300 1300 1300 1300 1300 1300Ply dimension length [mm] 1250 1250 1250 1250 1250 1250 1300 1260 700Displaced amount between inner 50 50 50 50 50 50 0 40 600 liner andcarcass ply in width direction [mm] Evaluation Weather resistance index100 98 98 98 98 98 94 98 99 Flex crack growth index 100 100 99 93 95 10089 95 95 Elasticity change index 100 97 99 97 97 97 88 94 97 Durabilitydriving index 100 98 98 98 98 98 81 93 98 Uniformity 100 100 99 99 99 9993 92 99 *Comp. F.: Comparative formulation **Ex. F: Example formulation

<Performance Test>

A performance test in the examples and comparative examples wasperformed in the following manner.

<Weather Resistance Index>

The inside of the inner liner of each tire was subjected to a weatherresistance test using Sunshine Super Long-Life Weather Metermanufactured by Suga Test Instruments Co., Ltd., under the followingconditions. Irradiation was conducted for 60 hours at a temperature in abath of 63° C., at a humidity of 50%, at 60° C., and with rainfall for12 minutes. The number of cracked portions in the inner liner after thetest was determined Using the value in Comparative Example 6-1 as areference value, a relative value of the number of cracked portions ineach of other comparative examples and examples were determined, and aweather resistance index was calculated by the following equation. Thegreater the value, the more excellent the weather resistance.

weather resistance index=(number of cracked portions in ComparativeExample 6-1)/(number of cracked portions in each example and comparativeexample)×100

<Flex Crack Growth Index>

The flex crack growth index was determined based on the evaluationmethod described above.

<Elastic Modulus Change Index>

Under the conditions similar to those for the flex crack growth test,the inner liner of each pneumatic tire was evaluated on the increasingrate of dynamic elastic modulus (E′) before driving and after drivingfor 20,000 km, using Viscoelasticity Spectrometer VES (Iwamoto Factory)under the conditions of a temperature of 70° C., an initial strain of10%, and a dynamic strain of 2%. Using the value in Comparative Example6-1 as a reference value, an elastic modulus change index was determinedas a relative value of dynamic elastic modulus (E′) in each comparativeexample and each example. The greater the value of the index, thesmaller the increasing rate of the elastic modulus, which is moreexcellent.

elastic modulus change rate=(elastic modulus after driving)/(elasticmodulus before driving)×100

elastic modulus change index=(elastic modulus change rate in ComparativeExample 6-1)/(elastic modulus change rate in each example andcomparative example)×100

<Durability Driving Test>

In a durability driving test, a driving distance until a tire wasdamaged was measured with oxygen being injected. Each prototype tire wasleft for 336 hours in an atmosphere of 90% of oxygen and a relativehumidity of 70%. Thereafter, the tire was mounted on a rim, and 100% ofoxygen was injected. The tire was left for 336 hours at an internalpressure of 350 kPa in the atmosphere of 90% of oxygen and a relativehumidity of 70%. Thereafter, the tire was mounted on a JIS standard rim15×6JJ, and 100% of oxygen was injected to prepare a tire having aninternal pressure set to 280 kPa.

Driving was started under the conditions of a load of 500 kg and a speedof 170 km/hour. A break-in was conducted for 10 minutes, followed bycooling. Driving was started again at 170 km/hour. The speed wasincreased by 10 km/hour every 20 minutes during driving, and the drivingspeed was measured until the tire was broken down.

The driving distance at the time of breakdown in each comparativeexample and each example was determined, and its relative value wascalculated as an index, using the value in Comparative Example 6-1 as areference value. The greater the value of the index, the higher thedurability driving speed, which is more excellent.

durability driving speed index=(driving speed at breakdown in eachexample and comparative example)/(driving speed at breakdown incomparative example 6-1)×100.

<Uniformity>

The uniformity was determined based on the test method described above.

<Evaluation Results>

In the examples of the present invention, both of the first layer andthe second layer were blended with an ultraviolet absorber and anantioxidant by 0.5 to 40% by mass relative to the elastomer component.It is recognized that the weather resistance index in each of theexamples has a value significantly higher than those in the comparativeexamples in which an ultraviolet absorber and an antioxidant in anamount outside of the above range were blended.

INDUSTRIAL APPLICABILITY

The method for manufacturing the pneumatic tire in accordance with thepresent invention is applicable to methods for manufacturing pneumatictires for passenger cars, trucks and buses, heavy equipment, and thelike.

REFERENCE SIGNS LIST

1: laminate; 2: inner liner; 3: unvulcanized rubber sheet; 4: cut sheet;5: drum; L: displaced distance (amount); 11: pneumatic tire; 12: treadpart; 13: sidewall part; 14: bead part; 15: bead core; 16: carcass ply;17: belt layer; 18: bead apex; 19: inner liner; PL: polymer laminate;PL1: first layer; PL2, PL3: second layer.

1-49. (canceled)
 50. A method for manufacturing a pneumatic tire havingan inner liner on an inner side of the tire, molding of a green tirecomprising: (a) an assembly step of preparing an unvulcanized rubbersheet and the inner liner having a width larger than that of saidunvulcanized rubber sheet, and bonding said inner liner and saidunvulcanized rubber sheet with end portions thereof in a width directionbeing displaced from each other by 50 mm to 500 mm in the widthdirection such that both end portions of said unvulcanized rubber sheetin the width direction are located on an inner side of both end portionsof said inner liner in the width direction to manufacture a laminate;(b) a cutting step of cutting said laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and (c) ajoining step of winding said cut sheet on entire circumference of thedrum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining said cut sheet such that the both end portionsof said inner liner in the width direction overlap each other, saidinner liner being a laminate of a first layer and a second layer, thefirst layer being a polymer composition containing 0.1 to 50 parts bymass of an organic derivative of a clay mineral relative to 100 parts bymass of a thermoplastic elastomer mixture containing 60 to 99% by massof a styrene-isobutylene-styrene block copolymer and 1 to 40% by mass ofa polyamide-based polymer which contains polyimide in a molecular chainand has a Shore D hardness of 70 or less, and having a thickness of 0.05mm to 0.6 mm, the second layer being disposed on a side of theunvulcanized rubber sheet, made of a thermoplastic elastomercomposition, and having a thickness of 0.01 mm to 0.3 mm.
 51. The methodfor manufacturing the pneumatic tire according to claim 50, wherein, insaid joining step, the both end portions of the unvulcanized rubbersheet in the width direction are joined using an unvulcanized rubberpiece.
 52. The method for manufacturing the pneumatic tire according toclaim 50, wherein said second layer is a thermoplastic elastomercomposition containing at least one of a styrene-isoprene-styrene blockcopolymer and a styrene-isobutylene block copolymer.
 53. The method formanufacturing the pneumatic tire according to claim 50, wherein 15 to30% by mass of an ethylene-vinyl alcohol copolymer is contained in apolymer component of the thermoplastic elastomer mixture of said firstlayer.
 54. The method for manufacturing the pneumatic tire according toclaim 50, wherein said styrene-isobutylene-styrene block copolymercontains 10 to 30% by mass of a styrene component.
 55. The method formanufacturing the pneumatic tire according to claim 50, wherein saidpolyamide-based polymer is a block copolymer composed of a polyamidecomponent and a polyether component.
 56. The method for manufacturingthe pneumatic tire according to claim 50, wherein said unvulcanizedrubber sheet is a carcass ply.
 57. A method for manufacturing apneumatic tire having an inner liner on an inner side of the tire,molding of a green tire comprising: (a) an assembly step of preparing anunvulcanized rubber sheet and the inner liner having a width larger thanthat of said unvulcanized rubber sheet, and bonding said inner liner andsaid unvulcanized rubber sheet with end portions thereof in a widthdirection being displaced from each other by 50 mm to 500 mm in thewidth direction such that both end portions of said unvulcanized rubbersheet in the width direction are located on an inner side of both endportions of said inner liner in the width direction to manufacture alaminate; (b) a cutting step of cutting said laminate to have a constantlength corresponding to a width of a drum to manufacture a cut sheet;and (c) a joining step of winding said cut sheet on entire circumferenceof the drum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining said cut sheet such that the both end portionsof said inner liner in the width direction overlap each other, saidinner liner being formed of a laminate of a first layer and a secondlayer, the first layer containing more than or equal to 60% by mass andless than or equal to 99.5% by mass of a styrene-isobutylene-styrenetriblock copolymer and more than or equal to 0.5% by mass and less thanor equal to 40% by mass of a polymer obtained by polymerizing a monomerhaving 4 carbon atoms, and having a thickness of more than or equal to0.05 mm and less than or equal to 0.6 mm, the second layer beingdisposed on a side of the unvulcanized rubber sheet, made of athermoplastic elastomer, and having a thickness of 0.01 mm to 0.3 mm.58. The method for manufacturing the pneumatic tire according to claim57, wherein, in said joining step, the both end portions of theunvulcanized rubber sheet in the width direction are joined using anunvulcanized rubber piece.
 59. The method for manufacturing thepneumatic tire according to claim 57, wherein said second layer has atleast one of a styrene-isoprene-styrene triblock copolymer and astyrene-isobutylene diblock copolymer, has a thickness of more than orequal to 0.01 mm and less than or equal to 0.3 mm, and contains apolymer obtained by polymerizing a monomer having 4 carbon atoms by morethan or equal to 0.5% by mass and less than or equal to 40% by mass of apolymer component.
 60. The method for manufacturing the pneumatic tireaccording to claim 57, wherein said polymer obtained by polymerizing amonomer having 4 carbon atoms is at least one of polybutene andpolyisobutylene.
 61. The method for manufacturing the pneumatic tireaccording to claim 57, wherein said polymer obtained by polymerizing amonomer having 4 carbon atoms satisfies at least one of a number-averagemolecular weight of more than or equal to 300 and less than or equal to3,000, a weight-average molecular weight of more than or equal to 700and less than or equal to 100,000, and a viscosity-average molecularweight of more than or equal to 20,000 and less than or equal to 70,000.62. The method for manufacturing the pneumatic tire according to claim57, wherein said styrene-isobutylene-styrene triblock copolymer has aweight-average molecular weight of more than or equal to 50,000 and lessthan or equal to 400,000, and a styrene unit content of more than orequal to 10% by mass and less than or equal to 30% by mass.
 63. Themethod for manufacturing the pneumatic tire according to claim 59,wherein said styrene-isoprene-styrene triblock copolymer has aweight-average molecular weight of more than or equal to 100,000 andless than or equal to 290,000, and a styrene unit content of more thanor equal to 10% by mass and less than or equal to 30% by mass.
 64. Themethod for manufacturing the pneumatic tire according to claim 59,wherein said styrene-isobutylene diblock copolymer is a linearcopolymer, and has a weight-average molecular weight of more than orequal to 40,000 and less than or equal to 120,000, and a styrene unitcontent of more than or equal to 10% by mass and less than or equal to35% by mass.
 65. A method for manufacturing a pneumatic tire having aninner liner on an inner side of the tire, molding of a green tirecomprising: (a) an assembly step of preparing an unvulcanized rubbersheet and the inner liner having a width larger than that of saidunvulcanized rubber sheet, and bonding said inner liner and saidunvulcanized rubber sheet with end portions thereof in a width directionbeing displaced from each other by 50 mm to 500 mm in the widthdirection such that both end portions of said unvulcanized rubber sheetin the width direction are located on an inner side of both end portionsof said inner liner in the width direction to manufacture a laminate;(b) a cutting step of cutting said laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and (c) ajoining step of winding said cut sheet on entire circumference of thedrum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining said cut sheet such that the both end portionsof said inner liner in the width direction overlap each other, saidinner liner including a polymer sheet containing more than or equal to0.1 parts by mass and less than or equal to 5 parts by mass of sulfurrelative to 100 parts by mass of a polymer component containing morethan or equal to 5% by mass and less than or equal to 40% by mass of astyrene-isobutylene-styrene triblock copolymer and more than or equal to60% by mass and less than or equal to 95% by mass of at least one rubbercomponent selected from the group consisting of natural rubber, isoprenerubber, and butyl rubber.
 66. The method for manufacturing the pneumatictire according to claim 65, wherein, in said joining step, the both endportions of the unvulcanized rubber sheet in the width direction arejoined using an unvulcanized rubber piece.
 67. The method formanufacturing the pneumatic tire according to claim 65, wherein saidpolymer sheet further contains more than or equal to 1 part by mass andless than or equal to 5 parts by mass of stearic acid, more than orequal to 0.1 parts by mass and less than or equal to 8 parts by mass ofzinc oxide, more than or equal to 0.1 parts by mass and less than orequal to 5 parts by mass of an age inhibitor, and more than or equal to0.1 parts by mass and less than or equal to 5 parts by mass of avulcanization accelerator, relative to 100 parts by mass of the polymercomponent.
 68. The method for manufacturing the pneumatic tire accordingto claim 65, wherein said styrene-isobutylene-styrene triblock copolymerhas a weight-average molecular weight of more than or equal to 50,000and less than or equal to 400,000, and a styrene unit content of morethan or equal to 10% by mass and less than or equal to 30% by mass. 69.The method for manufacturing the pneumatic tire according to claim 65,wherein said inner liner is a laminate of a first layer and a secondlayer, the first layer being a polymer sheet made of a polymercomposition containing more than or equal to 0.1 parts by mass and lessthan or equal to 5 parts by mass of sulfur relative to 100 parts by massof a polymer component containing more than or equal to 5% by mass andless than or equal to 40% by mass of a styrene-isobutylene-styrenetriblock copolymer and more than or equal to 60% by mass and less thanor equal to 95% by mass of at least one rubber component selected fromthe group consisting of natural rubber, isoprene rubber, and butylrubber, the second layer being made of a thermoplastic resin compositioncontaining more than or equal to 0.1 parts by mass and less than orequal to 5 parts by mass of sulfur relative to 100 parts by mass of athermoplastic elastomer.
 70. The method for manufacturing the pneumatictire according to claim 69, wherein the polymer composition of saidfirst layer further contains more than or equal to 1 part by mass andless than or equal to 5 parts by mass of stearic acid, more than orequal to 0.1 parts by mass and less than or equal to 8 parts by mass ofzinc oxide, more than or equal to 0.1 parts by mass and less than orequal to 5 parts by mass of an age inhibitor, and more than or equal to0.1 parts by mass and less than or equal to 5 parts by mass of avulcanization accelerator, relative to 100 parts by mass of said polymercomponent.
 71. The method for manufacturing the pneumatic tire accordingto claim 69, wherein said thermoplastic elastomer is at least oneselected from the group consisting of a styrene-isoprene-styrenetriblock copolymer, a styrene-isobutylene diblock copolymer, astyrene-butadiene-styrene triblock copolymer, astyrene-isoprene.butadiene-styrene triblock copolymer, astyrene-ethylene.butene-styrene triblock copolymer, astyrene-ethylene.propylene-styrene triblock copolymer, astyrene-ethylene.ethylene.propylene-styrene triblock copolymer, astyrene-butadiene.butylene-styrene triblock copolymer, andepoxy-modified thermoplastic elastomers thereof.
 72. The method formanufacturing the pneumatic tire according to claim 69, wherein saidsecond layer includes at least one of an SIS layer in which thethermoplastic elastomer contains a styrene-isoprene-styrene triblockcopolymer, an SIB layer in which the thermoplastic elastomer contains astyrene-isobutylene diblock copolymer, and an epoxidized SBS layer inwhich the thermoplastic elastomer contains an epoxidizedstyrene-butadiene-styrene triblock copolymer.
 73. The method formanufacturing the pneumatic tire according to claim 65, wherein saidstyrene-isobutylene-styrene triblock copolymer has a weight-averagemolecular weight of more than or equal to 50,000 and less than or equalto 400,000, and a styrene unit content of more than or equal to 10% bymass and less than or equal to 30% by mass.
 74. The method formanufacturing the pneumatic tire according to claim 72, wherein saidstyrene-isoprene-styrene triblock copolymer has a weight-averagemolecular weight of more than or equal to 100,000 and less than or equalto 290,000, and a styrene unit content of more than or equal to 10% bymass and less than or equal to 30% by mass.
 75. The method formanufacturing the pneumatic tire according to claim 72, wherein saidstyrene-isobutylene diblock copolymer is a linear copolymer, and has aweight-average molecular weight of more than or equal to 40,000 and lessthan or equal to 120,000, and a styrene unit content of more than orequal to 10% by mass and less than or equal to 35% by mass.
 76. A methodfor manufacturing a pneumatic tire having an inner liner on an innerside of the tire, molding of a green tire comprising: (a) an assemblystep of preparing an unvulcanized rubber sheet and the inner linerhaving a width larger than that of said unvulcanized rubber sheet, andbonding said inner liner and said unvulcanized rubber sheet with endportions thereof in a width direction being displaced from each other by50 mm to 500 mm in the width direction such that both end portions ofsaid unvulcanized rubber sheet in the width direction are located on aninner side of both end portions of said inner liner in the widthdirection to manufacture a laminate; (b) a cutting step of cutting saidlaminate to have a constant length corresponding to a width of a drum tomanufacture a cut sheet; and (c) a joining step of winding said cutsheet on entire circumference of the drum such that a cut surfacethereof extends in a circumferential direction of the drum and the innerliner is disposed on an inner surface side, and joining said cut sheetsuch that the both end portions of said inner liner in the widthdirection overlap each other, said inner liner being composed of a firstlayer disposed on the inner side of the tire and a second layer disposedin contact with a rubber layer of a carcass ply, said first layer beinga thermoplastic elastomer composition mainly composed of astyrene-isobutylene-styrene block copolymer, said second layer being astyrene-based thermoplastic elastomer composition, (1) at least one ofthe thermoplastic elastomer compositions of said first and second layerscontaining 0.1 to 100 parts by mass of a tackifier relative to 100 partsby mass of a thermoplastic elastomer component, or (2) said second layercontaining a styrene-isobutylene-styrene block copolymer by 10 to 80% bymass of a thermoplastic elastomer component.
 77. The method formanufacturing the pneumatic tire according to claim 76, wherein, in saidjoining step, the both end portions of the unvulcanized rubber sheet inthe width direction are joined using an unvulcanized rubber piece. 78.The method for manufacturing the pneumatic tire according to claim 76,wherein said tackifier has a weight-average molecular weight Mw of 1×10²to 1×10⁶, and a softening point within a range of 50° C. to 150° C. 79.The method for manufacturing the pneumatic tire according to claim 76,wherein said second layer is a thermoplastic elastomer compositioncontaining at least one of a styrene-isoprene-styrene block copolymerand a styrene-isobutylene diblock copolymer.
 80. The method formanufacturing the pneumatic tire according to claim 76, wherein saidfirst layer has a thickness of 0.05 mm to 0.6 mm and the second layerhas a thickness of 0.01 mm to 0.3 mm.
 81. The method for manufacturingthe pneumatic tire according to claim 76, wherein saidstyrene-isobutylene-styrene triblock copolymer has a weight-averagemolecular weight of more than or equal to 50,000 and less than or equalto 400,000, and a styrene unit content of more than or equal to 10% bymass and less than or equal to 30% by mass.
 82. The method formanufacturing the pneumatic tire according to claim 79, wherein saidstyrene-isoprene-styrene triblock copolymer has a weight-averagemolecular weight of more than or equal to 100,000 and less than or equalto 290,000, and a styrene unit content of more than or equal to 10% bymass and less than or equal to 30% by mass.
 83. The method formanufacturing the pneumatic tire according to claim 79, wherein saidstyrene-isobutylene diblock copolymer is a linear copolymer, and has aweight-average molecular weight of more than or equal to 40,000 and lessthan or equal to 120,000, and a styrene unit content of more than orequal to 10% by mass and less than or equal to 35% by mass.
 84. A methodfor manufacturing a pneumatic tire having an inner liner on an innerside of the tire, molding of a green tire comprising: (a) an assemblystep of preparing an unvulcanized rubber sheet and the inner linerhaving a width larger than that of said unvulcanized rubber sheet, andbonding said inner liner and said unvulcanized rubber sheet with endportions thereof in a width direction being displaced from each other by50 mm to 500 mm in the width direction such that both end portions ofsaid unvulcanized rubber sheet in the width direction are located on aninner side of both end portions of said inner liner in the widthdirection to manufacture a laminate; (b) a cutting step of cutting saidlaminate to have a constant length corresponding to a width of a drum tomanufacture a cut sheet; and (c) a joining step of winding said cutsheet on entire circumference of the drum such that a cut surfacethereof extends in a circumferential direction of the drum and the innerliner is disposed on an inner surface side, and joining said cut sheetsuch that the both end portions of said inner liner in the widthdirection overlap each other, said inner liner being composed of acomposite layer of a first layer disposed on the inner side of the tireand a second layer disposed in contact with said unvulcanized rubbersheet, at least one of said first layer and said second layer being madeof an elastomer composition containing an isobutylene-based modifiedcopolymer which is made of a polymer block (A) mainly composed ofisobutylene and a polymer block (B) mainly composed of an aromaticvinyl-based compound, and in which at least one of the blocks containsβ-pinene.
 85. The method for manufacturing the pneumatic tire accordingto claim 84, wherein, in said joining step, the both end portions of theunvulcanized rubber sheet in the width direction are joined using anunvulcanized rubber piece.
 86. The method for manufacturing thepneumatic tire according to claim 84, wherein the elastomer compositionof said first layer contains the isobutylene-based modified copolymer by10 to 100% by mass of an entire elastomer component.
 87. The method formanufacturing the pneumatic tire according to claim 84, wherein theelastomer composition of said second layer contains theisobutylene-based modified copolymer by 5 to 80% by mass of an entireelastomer component.
 88. The method for manufacturing the pneumatic tireaccording to claim 84, wherein a content of β-pinene in saidisobutylene-based modified copolymer is 0.5 to 25% by mass.
 89. Themethod for manufacturing the pneumatic tire according to claim 84,wherein said isobutylene-based modified copolymer has a weight-averagemolecular weight of 30,000 to 400,000, and a value of molecular weightdistribution (Mw/Mn) of less than or equal to 1.3.
 90. The method formanufacturing the pneumatic tire according to claim 84, wherein, in saidisobutylene-based modified copolymer, fβ-pinene is contained in astyrene block of a styrene-isobutylene-styrene block copolymer, astyrene-isoprene-styrene block copolymer, or a styrene-isobutylene blockcopolymer.
 91. A method for manufacturing a pneumatic tire having aninner liner on an inner side of the tire, molding of a green tirecomprising: (a) an assembly step of preparing an unvulcanized rubbersheet and the inner liner having a width larger than that of saidunvulcanized rubber sheet, and bonding said inner liner and saidunvulcanized rubber sheet with end portions thereof in a width directionbeing displaced from each other by 50 mm to 500 mm in the widthdirection such that both end portions of said unvulcanized rubber sheetin the width direction are located on an inner side of both end portionsof said inner liner in the width direction to manufacture a laminate;(b) a cutting step of cutting said laminate to have a constant lengthcorresponding to a width of a drum to manufacture a cut sheet; and (c) ajoining step of winding said cut sheet on entire circumference of thedrum such that a cut surface thereof extends in a circumferentialdirection of the drum and the inner liner is disposed on an innersurface side, and joining said cut sheet such that the both end portionsof said inner liner in the width direction overlap each other, saidinner liner being composed of a composite layer of a first layerdisposed on the inner side of the tire and a second layer disposed incontact with said unvulcanized rubber sheet, said first layer being madeof an elastomer composition containing an SIBS modified copolymer havinga styrene block moiety of a styrene-isobutylene-styrene block copolymermodified with an acid chloride having an unsaturated bond or an acidanhydride and having a thickness of 0.05 mm to 0.6 mm, said second layerbeing made of an elastomer composition containing at least one of astyrene-isoprene-styrene block copolymer and a styrene-isobutylene blockcopolymer, and having a thickness of 0.01 mm to 0.3 mm.
 92. The methodfor manufacturing the pneumatic tire according to claim 91, wherein, insaid joining step, the both end portions of the unvulcanized rubbersheet in the width direction are joined using an unvulcanized rubberpiece.
 93. The method for manufacturing the pneumatic tire according toclaim 91, wherein a blending quantity of the SIBS modified copolymer insaid first layer ranges from 10% by mass to 100% by mass of an elastomercomponent.
 94. The method for manufacturing the pneumatic tire accordingto claim 91, wherein said second layer contains an SIBS modifiedcopolymer, and a blending quantity thereof ranges from 5% by mass to 80%by mass of a thermoplastic elastomer component.
 95. The method formanufacturing the pneumatic tire according to claim 91, wherein saidfirst layer is a mixture of the styrene-isobutylene-styrene blockcopolymer and the SIBS modified copolymer.
 96. The method formanufacturing the pneumatic tire according to claim 91, wherein one ofsaid first and second layers is blended with a tackifier.
 97. The methodfor manufacturing the pneumatic tire according to claim 91, wherein oneof said first and second layers is blended with a rubber component by 5to 75% by mass of an elastomer component.
 98. The method formanufacturing the pneumatic tire according to claim 91, wherein saidfirst layer is blended with at least one of an ultraviolet absorber andan antioxidant by 0.5 parts by mass to 40 parts by mass relative to 100parts by mass of an elastomer component.